A while back there was a group buy hosted by Skhattane.

Unfortunately that group buy was not authorised by AVS and was therefore blocked and deleted from the site. Some of us though, did get in on the deal especially since it was posted for some time and seemed like a legit buy.

Anyways Skhattane did inform us that it would take a few months for the prisms made of BK7 glass and AR coated would take a few months to produce and then a couple of weeks to ship. It took a little while longer than expected and I was somewhat concerned wether I would ever get the prisms. I am happy to report that the prisms have made it here a'ok.

They were extremely well packed and shipped US priority mail. They actually came from PA. I only have opened one of the prisms which were carefully wrapped and it is in perfect order. I carefully held it up to look thru and see how the clarity appears and I can say that it is amazingly clear. Now I just need to work on an enclosure for them but it will probably be some time before I get to this as I am still working on my room. I temporarily set up my projector though for my son's b-day and if I can safely place them in front of the projector to see how they work I'll probably do that.

If anyone else is waiting for theirs they are on their way.

Thanks Skhattane maybe next time you can work with AVS to make it a smoother event.

Great to hear. I am waiting here in Canada with fingers crossed. Was shipping prepaid, or how much did it cost?

Luke

What a cur incidences, I was just thinking to my self (befor I looked into avs) about maybe how I could fallen for such a scamed and, then I tuned into avs and the first thread I looked at was yours. That makes me feel better.

Mine should comming soon to Hawaii. I should now be thinking about my containment box too. Please feel free to share ideas.

I have metel milling machines. I can shape metal to any design. If someone could come up with a good drawings I could make one for the contribetor and me.

But most of all Thanks for the INFO.

cool I am in your group so maybe soon for me I hope

Shipping in the US was 5 bucks. The place where they were ordered and shipped from ships anything to the US for 5 bucks. Not sure about Canada or HI but it should have been part of the payment.

I grabbed copies of pics from the original thread or from the french site (not sure which) of a couple of enclosures.

and

This enclosure is made of pexiglass it appears. The last pic is a diagram for the cuts used. The prisms are smaller than you might think so you wanna wait till you get them before committing to anything.

Then there's a simple solution like:

Sorry no photo account.

I wanted to add these pics because they illustrates how to a create case which allows for a passthrough mode with dimensions. Again I don't take credit for any of these they are pics from the French site. Thanks goes to them they've done a lot of hard work.

Yes they have done their home work, but I do have to question their prisms angles, especially the rear prism. Based on the diagrams, I believe that the image will not provide a true symmetrical stretch, as the front prisms essentially stretched the left side whist the rear prisms essentially stretches the right side.

Did anyone them actually build the unit with a pass through?

Mark

I am now worried about the size of these prisms. What are their dimensions? It looks like they are only 2.5" high. I don't think that they are large enough for my w9000. Does anyone now if they will work?

Luke

The largest prism face is 110mm x 70mm or about 4.5" x 2.75" at 20 degrees, so pretty small...

Mark

i'm still waiting for mine to show up in Sydney. i've been regularly checking updates on the french site w/babelfish and haven't worried that i'd been scammed. i plan to make a simple sliding enclosure such as skhattane posted. cant wait!

Yes they have done their home work, but I do have to question their prisms angles, especially the rear prism. Based on the diagrams, I believe that the image will not provide a true symmetrical stretch, as the front prisms essentially stretched the right left side whist the rear prisms essentially stretches the right side.

Did anyone them actually build the unit with a pass through?

Mark

I wondered about the prism angle when I saw the rear one more straight and the front one at more of an angle on some of the pics I saw, like one of the diagrams above. I did see a setup on the french site with a picture flashing back and forth of an enclosure switching from pass to strech. It had some sort of binding mechanism which only allowed for the prisms to turn so far, If I find it I'll link to it.

When I held up the prism to look through it did shift everything over so I am confident it will work.

I am now worried about the size of these prisms. What are their dimensions? It looks like they are only 2.5" high. I don't think that they are large enough for my w9000. Does anyone now if they will work?

Luke


The prisms are small compared to others. Most of us asked if the prisms would work with a particular projector because of this, and if Skhattane knew of someone that had previously used it he would tell us so. Since you have one of the newer 1080P projectors their might not have been someone who tried it out.

You can try the paper test to see how large an image is being projected on to a white sheet of paper 6-8" away from the projector. If it is about 4" you should be ok. Good luck.

plan to make a simple sliding enclosure such as skhattane posted.

I liked his enclosure as well, simple top and bottom with a bolt at each corner. I wondered if the sides being open though would cause a flury of reflections even though the prisms are coated. We shall see soon enough :D

I wondered about the prism angle when I saw the rear one more straight and the front one at more of an angle on some of the pics I saw, like one of the diagrams above. I did see a setup on the french site with a picture flashing back and forth of an enclosure switching from pass to strech. It had some sort of binding mechanism which only allowed for the prisms to turn so far, If I find it I'll link to it.

When I held up the prism to look through it did shift everything over so I am confident it will work.


My prisms are a bit less at around 14 degrees, but what I found when using two of the same angle (not any different from what you guys will doing) is that if you only moved the front prism, that only the left side will stretch. Yes you can get a full stretch by then turning the lens, but the stretch will not be symmetrical...

Mark

http://www.homecinema-fr.com/forum/viewtopic.php?t=29803723&postdays=0&postorder=asc&start=3030

This is the link to the French site with the rotating enclosure. I thought they used these prisms to make it, but it appears to be of the home brew variety. It's a little past half way down after the first enclosure.

Mark, the first pic in post #8 shows the prisms flat against each other, when shifted for stretch the opposite side becomes flat against the projector lens. Not sure of the properties of these prisms but it will be fun to see how they come together. I almost wish I had ordered a spare set for testing, now I have to be extremely careful.

Got mine today!!!! In perfect condition. Thanks SAM, where-ever you are...

http://www.homecinema-fr.com/forum/viewtopic.php?t=29803723&postdays=0&postorder=asc&start=3030

This is the link to the French site with the rotating enclosure. I thought they used these prisms to make it, but it appears to be of the home brew variety. It's a little past half way down after the first enclosure.

Mark, the first pic in post #8 shows the prisms flat against each other, when shifted for stretch the opposite side becomes flat against the projector lens. Not sure of the properties of these prisms but it will be fun to see how they come together. I almost wish I had ordered a spare set for testing, now I have to be extremely careful.

A thicker prism (ie 20 degrees) won't need as much angle as a thinner prism, but I think that you will find that the angles still need to be the same off the centre axis for both prisms. This has been well documented on both this site as well diyaudio.

It would change if the prisms used different angles, or were made from different materials, but in this case, both are BK7 and both have a 20 degree angle...

Mark

That's good news T_MINTON,

Are you ready to go with your set up? If you are, post some pics of what you end up doing.

Got mine today!!!! In perfect condition. Thanks SAM, where-ever you are...

I also got mine. I have not unpacked them. I hope they are ok.
But the concern is if they would work. They seem awfully small and they are
not identical as the package looks like and as CAVX points out that
could be a problem.

Anyway will wait and see if $126 works or if it is down the drain already.

Most likely I will sell one pair or both the pairs and will post a message.

If the mods are irresponsible enough to delete this thread or this post then
check videogon or ebay.

They seem awfully small and they are
not identical as the package looks like and as CAVX points out that
could be a problem.

No, they have the same angles, but the prisms' shapes are specified as front and rear, where the larger prism is the front...

Mark

I don't believe they are too small. It will be a while before I get set up...I may need some help from MARK about throw distance for these. I have an NEC HT 1000.Older , but stil a great picture. I am sure I need to move PJ closer to screen or I will be way too big. Plus I am gone next week to Gatlinburg and BRISTOL race.

I may need some help from MARK

I don't know how much help I'll be - I don't own a pair of these. You need to work off the smallest image size possible within the zoom range...

Mark

Curious Mark,

Does that mean start with the smallest image possible and go up from there? I understood for CIH that one would start with their preferred 16:9 image and then place the prism's in front to get 2:35.

I will most likely have to start/go with my smallest image size since i'm projecting from about 15-16' and have to account for speaker placement and masking which I will have recess to the sides or above.

So much to do, such little time.

Curious Mark,

Does that mean start with the smallest image possible and go up from there? I understood for CIH that one would start with their preferred 16:9 image and then place the prism's in front to get 2:35.

These prisms are small, so your TR is going to have to be quite high even though Sam did make a post in the now deleted thread that 1.4:1 would work, I seriously doubt that. I'm at 1.3:1 and the image in the front prism of my lens is just under the full width of 170mm, so no chance that 110mm is going to work on my system...

I will most likely have to start/go with my smallest image size since i'm projecting from about 15-16' and have to account for speaker placement and masking which I will have recess to the sides or above.

So much to do, such little time.

I suggest to start with the smallest image size, then move the projector back if you have the room and still want a bigger image. For so long, people have relied on the zoom on the projector for more light and larger image size. That is OK when there is no anamorphic lens involved, but now you have to fit that light inside a very small area and not clip (vignette) the beam...

Mark

Got it, I understand now.

Thanks for the tips. I'm getting eager, maybe this weekend I might try to start an enclosure. We'll see if time allows.

Oman and others,
Were you in the first batch or second batch? Mine was in the second batch and I got a message sometime in June from Skhattane that he would be sending them out end of July or so....

Second Batch,

I think first batch was quite some time ago. I got the same message about July but then there was a message on the French site that they had been delayed and were shipping in a week at the beginning of August. A third batch never took off. You should be getting yours soon.

well I unpacked the prisms tonight. It was very well wraped. Thanks.

They seem very well made.

I havent been abke to get the right placement. At least the
image coming through the prisms is very clear. My 16:9 image is very small.
Only 63'' wide as I changed the projector location from the previous location which gave me 77'' wide 16:9 image. The 2.35 image would then get too big.
So I moved the projector to another location.
I have Infocus IN72. I believe its throw ratio is 1.77 to 2.16. I am at full zoom so mine is 1.77 which I guess should be ok. The image on the second prism is not going out of the prism but like I said I havent got the right placement yet.

I need to check one of the posts in the other thread to get the right placement
of the prisms.

It looks promising so far

That's good news Mupi,

Have you tried to set them up like the first image in post 5? I would try that and then angle the rear prism as you go. Good luck.

yes I just tried it and I am able to get a nice rectangular image. I am
not playing an anamorphic DVD. I just tried ESPNHD. I just wanted to see
if I can get a nice rectangular 2.35 image. I had to tilt both the prisms
as they werent perfectly normal to the beam. That can be fixed as my
projector is probably tilted. Notthing is perfect yet.

There is some reflection. Mine is table mounted. There is reflection to the
left and back but not like the reflections from the mirror like Massillon Plaque
prisms. If I just keep my hand on the side and back the reflections are gone.
So putting a simple enclosure would get rid of the reflections.

Yes the angles of the 2 prims are the same. It is a good way of cutting the cost
by making the first prism smaller.

I thought the left and right edges were a bit blurry. It could also be the
overscan thing. Who cares about the edges.

I am going to ask my coworker to come to my place so that he can give his
opinion as he has more experience with HT. He can also take a picture.
I am sure he is reading this post :-)

I just wonder why the pro lenses cost $3000. Just due to monopoly.
I think with more and more people going the DIY route the
price of the pro lenses will drop soon.

The picture looks pretty good to me. I am sure it will look a lot better when
I play an anamorphic 2.35 DVD
With a $600 projector and $126 prism I cant ask for more.
My dream of watching a movie without bars seems to be finnaly coming true :-)

will post next week.

I just wonder why the pro lenses cost $3000. Just due to monopoly.
I think with more and more people going the DIY route the
price of the pro lenses will drop soon.

2 elements verses 5 (or more)...

Mark

I was in the last batch and received mine today. For the priced payed for coated lens and 5 dollar shipping to boot I feel this was a good gamble.

I have my 7210 hanging upside down so it's going to be while to test mine (until I can get my box and sled ready).

I have a existing pornamorph 100u (vertical compression). I will build my box around my panamorph's existing sled and bracket. Hope to have pictures someday.

Good to hear Mupi, glad you were able to get a good image.

jplmain, $5.00 to HI I don't think you'll get that anywhere else.

Guys post them pics when you get them, I'll try to do the same. I'm gonna try to start a wooden enclosure and probably line the top and bottom with something that will grip the prisms. I intend to use some sort of sled or slide system.

2 elements verses 5 (or more)...

Mark

and what are those extra elements?

MDF or aluminum enclosures? nuts and bolts for adjustment? mounts?

Even if the quality of the prisms is better and there are more
layers of coating it doesnt justify a whopping $3000

They dont have to strive to make such perfect lenses.
How many people here have a projector that is $5000 or more
to justify buying a $3000 lens. Just like there are budget projectors
like IN72 that has an image quality of a $5000 projector, there
could be a budget lens too.

All we need is something like sams prisms that works and that has a
simple enclosure. If someone wants a sled then they have to pay more.
It shouldnt cost more than 50 bucks to make a MDF enclosure.

and what are those extra elements?

MDF or aluminum enclosures? nuts and bolts for adjustment? mounts?


No, they are extra bits of purpose made glass that correct for focus, CA etc. If anyone says they don't need them, it is because they have not yet seen the improvement they make...

Even if the quality of the prisms is better and there are more
layers of coating it doesnt justify a whopping $3000

Allot of the expense comes down to the finish of the surface. Yes the DIY prisms look smooth with no visible surface markings to the naked eye, but under a microscope, they full of pits and grooves. To get the best finish takes time, and time is money...


They dont have to strive to make such perfect lenses.

It depends on who is buying I suppose...

How many people here have a projector that is $5000 or more
to justify buying a $3000 lens. Just like there are budget projectors
like IN72 that has an image quality of a $5000 projector, there
could be a budget lens too.

All we need is something like sams prisms that works and that has a
simple enclosure. If someone wants a sled then they have to pay more.
It shouldnt cost more than 50 bucks to make a MDF enclosure.

That is subjective...

Mark

Well, the volume produced & sold is less which jacks up the per unit price. Photographic lenses have more elements, motors, better housing and I bet are better finished than these prisms but they sell a lot more of them....

I guess currently only ball players are buying those $3000 prisms :-)

I was able to make a simple enclosure with wood & cork board to hold the prism's in place. I aligned the prism's according to the template that I posted above and I was able to quickly test them out. Like Mupi it wasn't perfect but it will work it's just a matter of fine tuning it. The thing is that I have the projector on a shelf over my head and had to hold the enclosure in front of the lens and try to line it up. My image was rectangular though so I am quite pleased.

I snapped some pic's of the enclosure and matierials used, I'll post when I get some time.

There's a package waiting at the post office for me! Come on monday!!!!

I got mine delivered yday. They are very nicely packed. I hv to build an enclosure and bring down the projector to do some tests.
Oman - any pictures on how you built the enclosure would be useful, thx

Can I get the info on where to order these lenses please ? ... send me a pm if necessary ;)

Can I get the info on where to order these lenses please ? ... send me a pm if necessary ;)

Sorry it was a one shot deal at (http://www.commandes-groupees.fr/viewtopic.php?p=4384). If you keep a eye on there site you might get chance to order when they get another batch lined up.

Someone on this thread (MUPI) ordered two pairs and might be selling one on ebay.

I just wonder why the pro lenses cost $3000. Just due to monopoly. I think with more and more people going the DIY route the
price of the pro lenses will drop soon. The "pro" category is Isco and Schneider. List on the Isco (III) is $5999, List on a Cinedigitar is $4200. So I'm not sure which "pro" lens you are speaking of that is $3k.

But regarding the former, they cost more becasue they are photographic quality lenses, with multiple spherical and cylindrical lens elements. They have adjustable astigmatism correction, and precision (i.e. pro telescope quality) housings. Curves cost more, in many places ;)

Hi GetGray,

I think he (Mupi) is referring to the Panamorph UH380 (http://www.panamorph.com/ModelUH380.html) which I already explained (a few posts back) has 5 glass elements not 2...

Mark

Here go some pics of what I came up with.

I used the the image on post 5 to get the outside dimensions of the enclosure. If you print it out it you'll notice that it isn't to scale, so like I stated it worked for the outside dimensions. Then I reduced the image on a photocopier to 90% and that brought the image of the prisms closer to scale and that is what I use on the inside of the enclosure to help align the prisms.

Finally this is how it all came to gether. I'll be recessing the screws, priming and spray painting for a nice finish. Also I'll be making some sort of bracket and mounting it to a drawer slide. A quick test showed it worked nicely, but I need to either mount or bring my projector down to fine tune. :cool:

I think he (Mupi) is referring to the Panamorph UH380 (http://www.panamorph.com/ModelUH380.html) which I already explained (a few posts back) has 5 glass elements not 2...Oops, sorry. Different conotatations for pro

Hi Oman,
Would be helpful to know the outside and inside dimensions and the thickness of the wood/cork board? Does it fit snug?

Well done Oman321, Sam would be proud ;)

Mark

Snowkirk,

The wood is 3/8 X 6 X 36 craft wood. If I did it again I would use 1/2" wood cause you might notice in my last pic one of my side panels split. It's ok I already replaced it, the 36" length left enough scrap.

I got all the material at Lowes. The cork board was a plastic backed disc for plant pots. It cut easily and worked like a charm. The prisms are nice and snug and I have held the enclosure in every direction to test out. The most important dimension is for the side panels, they measure 3 1/8" inches. Originally they measured 3&1/4 and they were sliding everywhere the 1/8th made all the difference. The cork board measures 3/16. The top and bottom pieces are 5&7/8" at the big end and 4&1/4" at the small.

Top and bottom were measured after the fact. The easy way was print out first image in post 5, then reduce to 90%. Cut out both images use bigger one for outside dimensions and smaller one for inside dimensions of cork board. Adhesive to glue cork boards, make sure you account for sides, you might have to trim a little extra from smaller image.


Sam, thanks.

I meant thanks Mark it was early when I posted, although thanks do still go to Sam.

So when are we going to see some screen shots?

Mark

The thing right now is that I have a temporary set up I did for my son's B-day at the beginning of the month, I am trying to figure things out with this. From my current projector location at about 16-17 ft. I am not so sure it's gonna work. It works but the image is taking over my entire 11ft.5in. wall.

I moved my projector to about 12 ft. last night but I haven't been able to test out yet. I'm not sure I want to do this because it would mean that I would have to change a few things i.e. my exhaust vent for the projector, outlet video wires. Also I have been testing regular 16:9 images because I haven't gotten a solution for anamorphic stretch yet. I'm thinking either HTPC or maybe the Key Digital scaler if it's still available when I'm ready.

I will be testing tonight hopefully from my new location and see what I can come up with. I can snap some pics but it wont look right unless I find that my DVD player might do the stretch. It's an upconverting panansonic and it has an extensive menu so im not sure.

For my sanity, and I think you've posted this before Mark. If I start with a 90in. width I would then multiply 90 X 1.33 to get a dimension 119.7?

Also I have been testing regular 16:9 images because I haven't gotten a solution for anamorphic stretch yet. I'm thinking either HTPC or maybe the Key Digital scaler if it's still available when I'm ready.

What source material are you running? Whilst HD might pose problem for some projectors, SD DVD (set to 16:9) should be able to be scaled using either "letterbox" or "4 x 3 zoom" in pretty much every projector except the Benq - w100 (which for reasons I can't work out does not have a letterbox mode)...

I will be testing tonight hopefully from my new location and see what I can come up with. I can snap some pics but it wont look right unless I find that my DVD player might do the stretch. It's an upconverting panansonic and it has an extensive menu so im not sure.

For the purpose of testing and initial set up, set it back to SD. The fact that you'll be using the full panel will be a huge PQ improvement anyway...

For my sanity, and I think you've posted this before Mark. If I start with a 90in. width I would then multiply 90 X 1.33 to get a dimension 119.7?

Your math looks good to me. Once the prisms are aligned correctly (and you need a 2.37:1 AR screen to do this), you will have a 1.33x stretch optical adaptor...

Mark

I was viewing 16:9 HD and SD. TNT was showing Forrest Gump and we have both versions of the station on Comcast Cable. With my cable box set to 480P on SD channels it creates a 16:9 image. instead of 4:3 when set to 480i.

I have an Epson HC 400 which offers some good aspect control but not vertical stretch. It was interesting because if offers a through mode for 16:9 HD & SD which reduces the image by about 10% overall but does not cutoff anything that I noticed. This might be a solution I could utilize perhaps if it comes down to it.

I quickly looked at the manual on line it states "Use Wide if you want to expand a 4:3 image to 16:9 so it fills the whole screen" so I suppose this is the mode I want on this projector.

I was viewing 16:9 HD and SD. TNT was showing Forrest Gump and we have both versions of the station on Comcast Cable. With my cable box set to 480P on SD channels it creates a 16:9 image. instead of 4:3 when set to 480i.

Sounds like it is looking to 16:9 for any HD input (not good, but nothing you can so - mine also does this), so set to 480i and see what happens...

I have an Epson HC 400 which offers some good aspect control but not vertical stretch. It was interesting because if offers a through mode for 16:9 HD & SD which reduces the image by about 10% overall but does not cutoff anything that I noticed. This might be a solution I could utilize perhaps if it comes down to it.

No projector (even the Cinewide from Runco) lists it as vertical stretch...


I quickly looked at the manual on line it states "Use Wide if you want to expand a 4:3 image to 16:9 so it fills the whole screen" so I suppose this is the mode I want on this projector.

So long as it clips the top and bottom off the image and does not stretch it...

Mark

Actually it states that it stretches left and right but leaves the center unchanged.

There is a note at the bottom of all the aspects that states " if you display a 4:3 image using the Zoom setting, the top and bottom will be cutoff" perhaps this setting then?

Here's a link to the page with the manual if you have the time and energy to take a peek it would be appreciated. It lists the aspects on page 27.

http://www.epson.com/cgi-bin/Store/support/supDetail.jsp?BV_UseBVCookie=yes&infoType=Doc&oid=75864&prodoid=63059180

I knew it wouldn't list it as V. stretch, I had previously asked and I was told the Epson's didn't offer it. Tough to get your head around all of this it took a while to understand CIH and as you can see I still have questions. Thanks again for the help.

Quick correction the cable box goes to 4:3 on SD when SD override is set to off. I will do that to see.

Oman,
Thanks for your response. Got the idea, trip to Lowes or HD this wkend.

There is a note at the bottom of all the aspects that states " if you display a 4:3 image using the Zoom setting, the top and bottom will be cutoff" perhaps this setting then?

Yes that is it, so the black bars are now what will be chopped off...

Quick correction the cable box goes to 4:3 on SD when SD override is set to off. I will do that to see.

The source must always be set to 16:9. The display will be set to a 4 x 3 mode. For optical stretched 16:9 (DTV), you simply use the native 4 x 3 mode or remove the lens and use 16:9 mode...

Mark

Ok, I got some pics. They're not great but its something, I'll give you a sample of one before and stretch and then 3 with lens in place.

This is my first attempt on screen pics so they're not fabolous. The last pic posted was the first one I took, I was setting the timer on the camera and then placing it down on an unlevel surface. So it's the camera at an angle not the image,for the rest of the pics I slightly held the camera up on that side.

After some testing with my setup I measured the image without and with the lens at my lowest zoom (the pics taken are with zoom set to about 1/3 or a little more). After calculating the measurements I realized that prisms are adding 1.55 to the image and need to be adjusted. Alas the Mrs. was hollaring for me to come up.

I noticed as I was reviewing my pics on my camera last night that the one of the plane with lens in place has a green push. I'm not sure if this is an anomoly of the camera or lens, I don't remember it like that on the screen so I will have to test that image again when I adjust the prisms'. The other stretched pics actually look better than the original shots and the white areas in those pics don't exhibit the same green tint. We shall see.

Hi guys,
I must be blind but I couldn't find where to order the French Prisms you are talking about. Is there another thread where they are described?
Thanks
Giorgio

crocowhile,

Read the first post, you'll see that their was an opportunity to buy these that was not authorised by AVS back March/April. That original thread has since been removed/deleted. This is more of a discussion of those that just recently recieved and will be using. Mupi might sell a second set he has, and some might later on sell theirs if not used.

You never know if the French forum mentioned earlier might offer another group, but you have to go there and use google to translate.

http://www.commandes-groupees.fr/viewtopic.php?p=4384

Ok, I got some pics. They're not great but its something, I'll give you a sample of one before and stretch and then 3 with lens in place.
Looks good, now I'm getting excited!

I noticed as I was reviewing my pics on my camera last night that the one of the plane with lens in place has a green push.

Could be the camera, I'd place more trust in what your eyes (or better yet a colorimeter) see on screen.

Good results so far and I look forward to a more refined version :)

Mark

Good news, color shift was something silly. Lose component cable :p

I also corrected for 1.33 vs. the 1.50-1.55 I was displaying.

Now another thing I wanted to try was vetical compression I didn't think it would work but here is something interesting...

I was able to make it happen, it was a little tricky but the first pic is vertical compression at lowest projector zoom the second was vertical compression at max zoom. The last two pics show how I placed the lenses. I didn't take exact measurements but you can manipulate to compress.

Now JPEG 010 doesn't look quite right (not stretched enough?) where 11 looks good. Interesting that you got the VC app to work...

You screen seems to show sag in the fabric. Are you using a frame to line this up?

Mark

mine arrived this afternoon.

small chip in the corner of the smaller prism, despite being very well packed :( may need to talk to sam about it if it affects the image.

this is a very high quality DIY product and I'm happy I made it into the group buy!

pics to follow soon...

Ok, some pic's after playing around.

Firstly, my Sanyo Z5 is currently mounted on top of a tall dresser to the left of my couch. It has extreme lens shift to the right and mild lens shift down. It is zoomed about midway. All in all, not ideal for putting prisms in front!

As a result I have some distortion but have a look at the pic's anyways:

test_setup: here you can see the Z5 on the dresser with the prisms mounted in front on a sheet of paper

anamorph_hcfr_crop_resize: This shows the distortion at the images edges but also shows that the stretch is preformed relatively uniformly across the image.

jarhead_HD_DVD-crop_resize: Shows a still of an HD-DVD being played with PDVD 7.3, yxy for the v-stretch, 2400Pro ati graphics card preforming hardware acceleration.

The last two images are of The Departed HD DVD, first without the lens (stretched by yxy) then with the lens for HE (horizontal expansion).

Yes, the projector must be positioned perfect first. Any off setting in the projector will only be magnified by the lens.

So you will be able to correct the pincushion, and you have some CA, are you happy with the purchase?

Mark

Mark I noticed 10 looked funny but it was zoomed somewhat I started with 51.5 width and got it to 68.5 with the prisms. If you notice the tower on the left the tower looks like my original pic 8. Also I didn't get the exact frame shot as the plane is a little higher up on the screen.

He-he, ya theres some sag in my bed sheet:D, no frame to line up yet still in costruction. Used a tape meausure last night where as the original pics were just eye balling. This was all setup for my sons b-day party and I have taken advantage of it for testing. It's not perfect but the kids had a blast. Also I needed a clamp that was supporting the center a little better. Luckily it doesn't sway too much.

Voicecoils,

Good job, sorry to hear about the chip but it doesn't seem to be a problem.
You might want to put the prisms on a hard surface and then use something like shims to slightly tip the prisms, this helps to square things up like MUPI mentioned somewhere above. FYI I was projecting from below so I had to slightly tilt up from the front.

He-he, ya theres some sag in my bed sheet:D, no frame to line up yet still in costruction.

It is amazing how much easier it is to do when your screen is 2.37:1. The other thing however is that your native 16:9 image (lens removed) also needs to be spot as well, so allot easier with side masking panels as well (which I don't have yet) either.

I was going to ask how do you intend to correct the pincushion, but having another quick look at your images and it seems your free of the problems for now. If it does cause a problem, will you curve the screen or simply projector that onto the side masking when you construct your screen?

You can see my ongoing AT project in this post HERE (http://www.avsforum.com/avs-vb/showpost.php?p=11343680&postcount=15)...

Mark

I Wanted to ultimately have a curved screen If I go with 2:35, if anything for the look of it but also to address any pincushion. I have a contact for a local metal fabricator that I hope will be able to help. Like you said it doesn't seem to be an issue at the moment at the sides but I do notice a slight curve at the bottom you might notice on pic 4 in post 62. Much more pronounced on voicecoils streched pics but his prisms arn't tilted which helps to square things up.

I'm kind of torn because if I do a 2:35 screen I will have a small 16:9 screen where as If I do a large 16:9 screen I can still do a large 2:35 screen. That's why I was excited to be able to make V. Compression image work. I hope to put my projector back to where I was testing originally make a different enclosure for vertical and see if it works from there. I can then use the full panel and come up with a masking system.

I've seen your progrees Mark, good stuff I like your solution for the speakers & AT screen. I've also followed your progress with the Aussie Lens, impressive work. One of the many reasons i'm glad your chiming in to help out.

As a side note I put the coated sides of one of the prisms towards the projector lens to see how much light shines through... nothing but blackness.

Thank you oman321. I found the thread on the french forum, I'll try to keep up with them.

Yes, the projector must be positioned perfect first. Any off setting in the projector will only be magnified by the lens.

Mark

Yes I will need to find a proper home for the PJ, centered with the screen.

In your experience, is projector height relative to the screen a critical factor? In other words, is the best image achieved with the projector lens at the centre of the screen?

I could potentially put the projector on a shelf directly over my head (centre of the screen height and width). But if it's not a big issue it would be more convenient to have it higher up (especially for playing Wii!).

So you will be able to correct the pincushion, and you have some CA,


Does position of the prisms relative to the projector, position of the projector relative to the screen, position of the prisms relative to each other, and/or zoom affect CA?

are you happy with the purchase?

At half the price of the next cheapest options I know of, I'm quite pleased with an AR coated optical glass product.

But, if the prisms only cost $8 each from surplus shed (like their other prisms) then the price the group buy paid seems a bit high. Still, I've not no regrets even though my girlfriend doesn't seem so impressed so far :rolleyes:

Yes I will need to find a proper home for the PJ, centered with the screen.

In your experience, is projector height relative to the screen a critical factor? In other words, is the best image achieved with the projector lens at the centre of the screen?

I could potentially put the projector on a shelf directly over my head (centre of the screen height and width). But if it's not a big issue it would be more convenient to have it higher up (especially for playing Wii!).

It will depend on the projector, but most home theatre projector work off one plain (either top or bottom) depending on how they are mounted. You need to mount the projector as straight as you can (no key stoning), which generally means flush to either the top or bottom...


Does position of the prisms relative to the projector, position of the projector relative to the screen, position of the prisms relative to each other, and/or zoom affect CA?
Not really, CA is caused by the first prism as it breaks the (white) light into a spectrum. The second prisms can reform this light back to white light, but only when the two prisms are set up like a pass through mode. Because the placement of the prisms is staggered to form the anamorphic stretch, the light never quite reforms and the results are CA or colour fringing at the edges.

The only way to correct this is to use a second set of prisms made from a different type of glass that is then bonded to the first set to form an achromatic doublet - which is one project I am working on.

At half the price of the next cheapest options I know of, I'm quite pleased with an AR coated optical glass product.

But, if the prisms only cost $8 each from surplus shed (like their other prisms) then the price the group buy paid seems a bit high. Still, I've not no regrets even though my girlfriend doesn't seem so impressed so far :rolleyes:The cost is relative to the size of the prism (the amount of glass used), the type of finish, optic coatings etc. He would have had to have a minimum order as well to get his price down. I bet they cost more $8ea, mine are way more than that even when buying in bulk...

Mark

The $8.00 prisms are not the same, these are special ordered and a little bit bigger.

I made a vertical enclosure and took some pics. The first 2 pics are the prisms positioned as I showed above, this works but I had to reposition the lens on the projector. I had better results by positioning the enclosure as in the third pic (upside down basically)for less proj. lens adjustment.

This is the result of before, stretch, compress.

mine arrived this afternoon.

small chip in the corner of the smaller prism, despite being very well packed :( may need to talk to sam about it if it affects the image.

this is a very high quality DIY product and I'm happy I made it into the group buy!

pics to follow soon...

I also found a chip at one corner of one of the prisms. Just a coincidence
that you also noticed the same. It is at the corner so it doesnt affect the image I guess.
I havent yet tested the prisms with a DVD. But looking at the pictures and not much feedback here, I dont have high hopes. So most likely I might sell my pair of prisms but of course it has a chip.

I also found a chip at one corner of one of the prisms. Just a coincidence
that you also noticed the same. It is at the corner so it doesnt affect the image I guess.
I havent yet tested the prisms with a DVD. But looking at the pictures and not much feedback here, I dont have high hopes. So most likely I might sell my pair of prisms but of course it has a chip.

No need to have such poor confidence :) Most of us need to build an enclosure and continue adjusting before reporting back further. Have you looked through the HCFR threads or the Commandes-groupee ones? More then 165 people have these exact prisms now (most are french) and the continued interest on french forums for group buys should instill some confidence :)

I'm not too upset about my chipped lens, the package WAS very well packed, but the contents are delicate and it did travel well over 8,000 miles :eek:

I plan to better position my projector, get an enclosure made, and report back with some more pic's.

I suppose DIY is not for everyone and DIY anamorphic lenses are really still frontier HT territory (although heaps of hard work has already been done by CAVX, diyaudio.com, french crew etc).

I built an enclosure and tried these prisms. Got a rectangular image and noticed slight pincushion in the middle. For the money paid, I am satisfied. I will probably be able to take it to my friend's place and test it against his properly ceiling mounted Optoma HD80.

Mupi - if you are selling ur extra prisms, send me a pm, I can check with my friend if hes interested.

Don't fret Mupi,

People are still setting things up, I was just kind of anxious because I have a temp set up that needs to come down. The pics have been better than I expected, I tried to capture what I'm seeing but the pics never do what your seeing justice. Also, like we mentioned above pincushion on the sides hasn't really been an issue as you often find on a anam. prism setup

I looked last night and found a tiny chip at the corner of my large prism doesn't affect the image at all.

I was trying to look through the French site to see if they had any new developments with the prisms coming in and one guy got a prism that had a one inch chip with crumbled glass.

Snowkirk,

I meant to request pics of what you did. Did you go with something similar?

Oman,
I did one similar to yours(thanks for the details). I will test it with my friend's Optoma HD80 and see how it looks

well I tested the prisms today with a DVD.
I noticed that the focus wasnt as good as the image without the
prism. I also noticed that all 4 edges werent straight at all. They were
bowed and I couldnt get them straight. I also tried to reduce the
zoom on my IN72 but I still got the bow. Already the image isnt that
big. The 16:9 image is only 35mm tall. The 2.35 image is about 83x35mm.
Not a bad 2.35 image size but the clarity wasnt there. I also felt that the
bigger 2.35 image wasnt as bright as the smaller 2.35 image (i.e the one inside
the 16:9 area with black bars).

BTW is pincushioning same as the bowing of the edges?

I can see CA as the edges are not sharp. There is a bluish ghost kind of thing at the
left and right edge. But that can be managed using black borders.

Anyway... I might try a couple of more time this week end. I dont think the
image is going to get sharper. At least if I can find a way to keep the edges straight
I could live with it. My projector placement is fine because the 16:9 image is perfect.
If I have to zoom down all the
way to get rid of the bow then there is no point doing it because the image size
will be too small. I would rather watch a larger 2.35 image with bars than a tiny not so sharp one without bars :-)

The images in the other thread (crystal factory prisms) seem to be a lot
better. They seem to have perfectly straight edges.

Now I know why the commercial lens manufacturers strive for perfection.

Just curious: The Sams prisms I got were shipped by surplusshed in PA. The lower right corner of the receipt was cut and removed.
They also sell a lot of optical stuff including the $8 prisms. In fact I bought those $8 prisms from ebay and
since the concept worked I wanted to try bigger ones. I tried the Masillion Plaque
prisms but they gave a lot of reflections. Sams prisms also give reflections but they
can be eliminated with an enclosure.

So are these so called Sam's prisms nothing but prisms from surplusshed?
Why were they shipped from surplusshed?
Why was a portion of the receipt cut and removed?


Final note: after my final testing this weekend if I still feel buyer's remorse :-)
I will be selling mine. Like I mentioned and like others have mentioned there is
a tiny chip at one corner of one of the prisms. I paid $126.80. I will sell them for
$110. I guess I can pay for the shipping with in US if it is like 10-15 bucks.
My friend has not seen the prisms. If he also decides to sell after watching the image, will let you guys know. I dont like to put it on ebay as I dont want to explain all this story. People here already know the story so I dont have to explain :-)

BTW is pincushioning same as the bowing of the edges?

Yes, where the centre (vertically) is not as tall as the edges, and same happens horizontally as well, though not as obvious...

Now I know why the commercial lens manufacturers strive for perfection.

Yes there is a bit more to it than just stretching the light which is why the commercial lens cost so much more - correction elements etc...

So are these so called Sam's prisms nothing but prisms from surplusshed?
Why were they shipped from surplusshed?
Why was a portion of the receipt cut and removed?Maybe he had them amde there and it was easier (more cost effective - shipping was included) to have them dispatched from there rather than paying freight to France (including an import fee), then having to mail prisms back to the US...

Mark

Mupi,

I wish I had taken a pic of my shimmed and tilted original enclosure. Based on your finding I tilted the enclosed prisms to best square things up, also during the tilting it seems to help the CA on the left and right. Only the best Lens' will be able to effectively deal with this. Unless Mark comes up with a DIY solution.

At times when I was taking the lens in and out I slightly had to refocus to achieve the best picture. I would mostly notice when there were words or the menu on the screen.

I am not certain but when I saw the packing slip, I assumed that this is where Sam ordered the prism's from. They advertised shipping to anywhere is $5.00 and this is what Sam added for shipping I believe. They are special ordered from what I can gather from translating the French site. The piece removed from the packing slip is probably a factory confirmation of one pair or 2 pairs etc... being placed in the package on a specific order. Good luck with your the rest of your testing, I gotta get back to construction.

BTW you got a better exchange rate than me, I ended up paying $135.00:(, that's ok for the price I think they're good:)

Was there an item number or SKU on the packing list?

If I still have it I'll check tonight, but you gotta have 50 produced to get them thus the reason Sam organized the unauthorized group buy.

Was there an item number or SKU on the packing list?

There is some item lookup code which is L9513D

I guess Samy has some explanation to do here :-)

BTW in the picture posted by OMAN321 (010.jpg) I dont see any pincuchioning
or barrel distortion. If my picture was as rectangular as 010.jpg I would accept it.
OMAN321: did you have zoom turned all the way down.
It is also possible that not all the prisms that Samy made are identical.
I am also surprised to see the ampunt of reflections from a coated prism.
It is not as bad as the Masillion Plaque prisms but for a coated prism
it seems too much. Well cant complain for $126.80.
I just wish that the image were rectangular. I can also live with CA.

Mupi,

I tried searching Surplus shed with that item number, nothing came up.

As far pic 10 I was I had zoom set to a little less than a 1/3. You'll definately need an enclosure and depending on projector placement you'll need to tilt the enclosure to square things up.

FYI: At Lowe's I saw a place mat in the cabinit area I might have used instead of the cork board if I had found that first.

There is some item lookup code which is L9513D

I guess Samy has some explanation to do here :-)

Thanks! As someone else said nothing came up. Oh well...

I got my french prisms yesterday, they were packed great, and in perfect condition. I made a first attemp to use them with my w9000 which has a huge lens, that is recessed quite far back. I got a decent picture on the screen, but because the light was sooo close to the edges of the prisms, it caused some reflections to the left and right of the projector.

I need to spend more time tweeking them, as I just set them on some books infront of the projector. I was quite impressed at how easy it is to get them lined up for a 2.35 stretch. It was only about 10-15 minutes until I had the screen filled.

The onscreen image looked pretty good, but I still don't know if these are large enought for the w9000. I am going to get a little more creative with the stand, and possibly build a box. If I can't get them to work I will likely go for the ausiemorphic or bite the bullet for the 380.

Luke

Ok, I'm excited again about CIH.

I tested out where the screen will be ideally placed which is 21" away from the wall in false wall setup. My projector being also placed at it's ideal spot produced an image at min. zoom of 82.5". So 82.5 x 1.33 = 109.725 approx 110" width <--->. My room is about 11'.5" wide, but hey that still leaves a foot+ on each side so plenty of space.

The 82.5" 16:9 screen is approx a 95" screen diagonally which is a good 16:9 screen for the room. The Mrs. thought a 100" which resulted in 115" diag. was just to overwhelming. So this results in a 2:35 screen which is 119.5" diag. So im back in with Horizontal Expansion it would seem, it will be more definative as I near completion of the room.

My room is about 11'.5" wide, but hey that still leaves a foot+ on each side so plenty of space.

At least you've got room for side masking :)

Mark

Hmmm... hadn't thought of the side masking. It would seem that it would fit if I make the screen borderless. My masking would need to be 13.75" and I would only have 14" on each side after a 110" screen. I think im gonna do drop down masking it would probably be a little easier to fit in and work out within a soffit above the screen.

I was wondering if there is any interest in having a metal, powder coated enclosure, cut with a plasma cutter and precise to the french prisms? I will hopefully have a prototype within 2 weeks and I am pretty sure I can get em done very reasonably if there is any interest. Of course I will go through Alan first if it comes to that.:)

I'd be interested to see the prototype.

I was wondering if there is any interest in having a metal, powder coated enclosure, cut with a plasma cutter and precise to the french prisms?

I'm interested, keep us updated :)

I'll support your effort.

I am gonna do it for myself anyway. He said he could do whatever I want. SO if there is anyone that can design in autocad, he could use that to set up his plasma cutter and viola!. Otherwise I am gonna have to rely on the french site or design one myself. Since I am his Mailman, he said he could give us a good deal...lol This is gonna take a few weeks so I will start another thread when I get mine done. I need to see if I can fine a good passthrough design for those that want that option.

SO if there is anyone that can design in autocad, he could use that to set up his plasma cutter and viola!. Otherwise I am gonna have to rely on the french site or design one myself.

Perhaps a bit of inspiration:

http://www.users.on.net/~michaelcarey/pics/lens/index.html

I'm not interested in passthrough, to complicated of an enclosure, just a simple thin compact box that can be mounted to a little sled.

I think you are right VC. I certainly wouldnt want to embellish on your design tho. But you have given me direction.thanks

I think you are right VC. I certainly wouldn't want to embellish on your design tho. But you have given me direction.thanks

Not my design, an early Aussie adaptation of the CAVX Aussiemorphic product.

With a plasma cutter a fancier or neater fitting box could be made. The example I liked to could probably be done with any metal cutting tool and a decent vise for the bend. Additionally, something bolted together could flat pack for easy shipping.

I think you are right VC. I certainly wouldnt want to embellish on your design tho. But you have given me direction.thanks

Any progress on your efforts T_MINTON? Any ballpark figures of what your source might be able to get something like this done for?

As I mentioned, I had to build a prototype. I have done that, sorta. I am no carpenter or designer. I have a design that is simple so the cost will be as minimal as possible. Having said that, if you or anyone has a design that can work email it to me with measurements etc, Then I can take that to my friend and get us a quote.Otherwise, I work as aletter carrier full time and overtime, so my fiddling is on the weekend usually. I do have it up and I will take pics soon. It is crude at best but it does work well. I will keep you posted on further developements. tonyminton@gmail.com:)

The best I have is the designs I attached at the beginning of thread in post 5-8 from the french site. There are some good pics with metric measurements in post 8 I believe with an enclosure which can be adapted to pass through. Other then that I have the enclosure I came up with in pics on post 47 48 & 49, which is a simple wooden enclosure made of 3/8 hobby craft wood. Below I pasted a response to Snowkirk as far as the dimension of the enclosure.
quote:
I got all the material at Lowes. The cork board was a plastic backed disc for plant pots. It cut easily and worked like a charm. The prisms are nice and snug and I have held the enclosure in every direction to test out. The most important dimension is for the side panels, they measure 3 1/8" inches. Originally they measured 3&1/4 and they were sliding everywhere the 1/8th made all the difference. The cork board measures 3/16. The top and bottom pieces are 5&7/8" at the big end and 4&1/4" at the small.

Sorry guys, still working on it.

No worries, we eagerly wait :D

I'm in the midst of working in my dedicated space and now that everything from my temp. setup is down things are moving along a lot quicker.

Looking foward to what you come up with, keep us updated.

Well I have "working model" just need tobe sure I can get a full range of adjustments as far as angles. I am flying by the seat of my pants, mostly because I am not quite as smart as the EXPERTS that brought all this to us in AVS. The case should be easy enough to do but becasue everyone's install is different I will only be offering a case for the prisms and not a complete install kit (for clarification)I will post some early pics tonight or tomorrow if work permits. My folks are in from Fla. so I have been visiting.

I will be selling both the pairs. If anyone is interested please see my reply to the thread that was started a few days ago or you can also scroll back in this thread to my post about selling my prisms.

PRISM DIMENSIONS:

BTW Here are the prism dimensions as some of you had asked via PM

The first lens (one closer to the projector) is shorter than the second.
Both are of same height and angle. I dont know the angle off hand. I have
to get a calculator and compute it.

First Lens: Length 3 3/8 inch (this is the length of the slanted face)
Height 2 3/4 inch

Second Lens: Length 4 2/8 inch (length of slanted face)
Height 2 3/4 inch

PRISM DIMENSIONS:

I dont know the angle off hand. I have
to get a calculator and compute it.

20 degrees...

Mark

Hello Everybody!!!
The prisms you are all refering to where made by us - Surplus Shed

We now have them available on our website and will be stocking them on a regular basis.

Here's the link:

http://www.surplusshed.com/pages/item/l9113d.html

We only have 8 in stock right now but are having more made and they will arrive in about one month.

Please let us know if everything is described properly or if we should add anything to our desription.

Thanks!
Brent Gilson
Surplus Shed

Brent,

When using a DLP projector to play a movie there are black bars on the top and bottom (widescreen), when positioned correctly, these prisms remove the black bars by stretching/correcting the image with no distortion.

This come from your website is totally inaccurate. The projector removes the black bars through a process we shall simply call "scaling". As a result, the geometry is affected (the image appears tall and thin as if vertically stretched). When the prisms are placed in the light path (with correct alignment) they optically restores the geometry through horizontal expansion, allowing the projection of films in cinema scope the way they were meant to be seen...

Mark

Glad to see your carrying these as a regular stock item now. From my initial testing with these I am very pleased with the product.

As Mark says though your description is not accurate. The prisms restore the geometric shape of the image after its been stretched by the projector or a video scaler or even a dvd player or Home Theater PC. Many ways to do what's reffered to as a vertical stretch. Prisms are then used to horizontally stretch the image for Costant Image Height or in some cases Vertically Compress the image for Constant Image Width. To purpose is to get rid of the black bars and increase resolution. Also it's not only a DLP projector which you can use. It is better described as a digital projector which would better refer to LCD, DLP, LCOS, SXRD, etc...

Thanks for the info guys!
Our website is updated every Sunday so we'll make the corrections then.

Sometimes we just make optics for people and have no idea what they are using them for..

Check out the 2:35 main forum, this is a subforum of that section. In particular check out the the "official 2:35 screen picture thread" which is a sticky at the top. It will show you what people are doing with different prisms and lens setups.

Just a word of caution though, technically your not able to come on to the forums to sell your products. So while it's nice to let everyone know it's available to the masses, check out the forum rules for what you can and cannot do.

Now that I stated that, is it possible for you guys to create slightly larger(taller) prisms. Just curios, my prisms are fine for my projector, but the lens' don't work on every projector due to their size.

We can make bigger prisms but it will require at least 50 to be made.

If you can spark some interest and get at least 25 people to commit to an order, we can have them in production.

We would need detailed specs with a drawing if possible. From there a sample would be made, sent to you for approval, then a 25% deposit would be needed to start production.

Our email is: surplushed@aol.com all specs would go there.

We saw there were quite a few people looking to get the prisms and we just wanted to let them know where to get them. Sorry for any misunderstanding.

Cool,

For me the existing prisms work, but for others who might be interested it's nice that it's possible. I believe all the dimensions other than the height would be the same. The idea is for the projectors beam to be able to fit inside the prism area without being obscured by the AR coating. Right now the prisms are about 2.5" tall they would need to be about 3.5 to 4" tall for them to work with most projectors.

Don't get me wrong, I'm quite pleased to know that you're making the prism's more regularly available (especially if something happens to mine by accident), just didn't want for you to get in trouble with the forum moderators. It's a great place for people to learn, trade information, get ideas, etc... but they have rules about commerce to make it fair to their sponsors. Like I said check out the various 2:35 threads to get an idea of what people are doing.

WARNING: this is an addictive hobby/way of life and you will quickly find yourself looking at AVS every chance you get with a computer. You have been warned.:D

The the chat on anamorphic lens home made cinema scope screens and masking systems. NOTE...Not for people looking to sell their products.

We can make bigger prisms but it will require at least 50 to be made.

If you can spark some interest and get at least 25 people to commit to an order, we can have them in production.

We would need detailed specs with a drawing if possible. From there a sample would be made, sent to you for approval, then a 25% deposit would be needed to start production.

Our email is: surplushed@aol.com all specs would go there.

We saw there were quite a few people looking to get the prisms and we just wanted to let them know where to get them. Sorry for any misunderstanding.

Be careful, because Sam got banned for the Same thing. Did you check your PM?

Mark

T_MINTON,

Any chance of seeing that prototype? Any update as far as your contact being able to produce the enclosure?

Thanks.

Hello Everybody!!!
The prisms you are all refering to where made by us - Surplus Shed

We now have them available on our website and will be stocking them on a regular basis.

Here's the link:

http://www.surplusshed.com/pages/item/l9113d.html

We only have 8 in stock right now but are having more made and they will arrive in about one month.

Please let us know if everything is described properly or if we should add anything to our desription.

Thanks!
Brent Gilson
Surplus Shed

So what exactly is the type of glass used.

Any reason why the prism ruins the focus of the image. I agree that these
prisms could be expected to cause distortion to the edges of the image but at least if they do not affect the focus it might be worth as a cheap alternative for CIH.

BTW: I still have one more pair left. It has a little chip at one corner but it
does not affect the image. I bought this through Sam for $126 (yes it was shipped
from surplusshed, PA)

Asking $95 + S&H. I sold one to a guy in Canada. The UPS cost to Canada was $12.
I would presume it would be under $10 within US.

I am sure the prisms that you buy from Surplus Shed would also have chips
like others here had reported :-)

So what exactly is the type of glass used.

Any reason why the prism ruins the focus of the image. I agree that these
prisms could be expected to cause distortion to the edges of the image but at least if they do not affect the focus it might be worth as a cheap alternative for CIH.

BK 7 @ 20 degrees...

Mark

So what exactly is the type of glass used.

Any reason why the prism ruins the focus of the image. I agree that these
prisms could be expected to cause distortion to the edges of the image but at least if they do not affect the focus it might be worth as a cheap alternative for CIH.

Mupi have you tried any other lens system?

I have read before that others need to slightly refocus their image when using a prism based lens. Not sure if that's the norm or not but I have very good vision and from when I was testing I can't recall it being a major problem. I might have needed to very slightly adjust to re-focus.

I have read before that others need to slightly refocus their image when using a prism based lens.

You shouldn't have to refocus the image if your moving the lens in/out of the
light path, but once focused, you may notice that the image is sharp in the centre and then progressively becomes less sharp towards the edges. Some of the loss in focus could be due to the CA that is virtually 0 in the centre and increases towards the edges.

Only corrective elements can fix this...

Mark

Now that you mention that, it think it was someone switching from stretch to passthrough mode that was having issues. I still think the image looks good/great for the cost.

And again, only corrective elements can fix this...

Mark

Mupi have you tried any other lens system?

I have read before that others need to slightly refocus their image when using a prism based lens. Not sure if that's the norm or not but I have very good vision and from when I was testing I can't recall it being a major problem. I might have needed to very slightly adjust to re-focus.

Nope I havent tried other lens systems. I had the Mallison prisms but
I returned them as they caused too much reflection.

With the French prisms I had to adjust the focus a bit. Not that the image was blurry but it wasnt as sharp as the image without the prism. The image without the prism is so nice that I could not live with the image with the prism even though it is only $126. So I decided to get rid of them. I have already sold one pair. The second one is up for sale.

I guess people should stop selling all these cheap crap claiming that they can be used as anamorphic lens. There is no way a DIY lens can beat the image from the commercial lens.

If the size of the 2.35 image is the only thing one cares about, then these cheap options may be ok but just bigger isnt better for me. I would rather watch a small but prestine image straight from the projector than a big but lousy image through the prisms.

BK 7 @ 20 degrees...

Mark

well you and I think they are BK 7. what is the guarantee that those pieces of glass are in fact BK 7. They could be just as bad as any other $8 prisms they are selling. I also doubt if they are coated considering how much they reflect. They arent as bad as mallison prisms but for coated prisms they put out an awful lot of reflections.

well you and I think they are BK 7. what is the guarantee that those pieces of glass are in fact BK 7. They could be just as bad as any other $8 prisms they are selling. I also doubt if they are coated considering how much they reflect. They arent as bad as mallison prisms but for coated prisms they put out an awful lot of reflections.

BK7 is pretty much the same as Crown Glass and is optically clear and not that expensive which is why it commonly used. Allot of the final image quality depends on the finish of the faces and the finer the finish, the better the result, but the more you pay. Having received quotes as high as $10.5K for four BK 7 prisms, would suggest that $126 is indeed entry level. It is not to say that those prisms could not be polished to much higher spec, just the price would go up dramatically.

I guess people should stop selling all these cheap crap claiming that they can be used as anamorphic lens.


No, one should not expect ISCO III performance from just 2 prisms that cost just $126.00. The 2 prisms lens works to a certain level (entry) and has been well documented to have faults - CA and some focus). It has just 2 elements after all, and it needs at least 5 (CA correction as well as focal correction) to qualify as "high end" product and you can be assured that even from a DIY end, it will cost way more than $126.00 in parts alone...

Mark

I guess people should stop selling all these cheap crap claiming that they can be used as anamorphic lens. There is no way a DIY lens can beat the image from the commercial lens.



Wow. Pretty high expectations for $100 anamorphic lens.

The fact is, these CAN be used for an anamorphic lens. If you want commercial quality, please buy a commercial lens--they have all kinds of correction features.

But these prisms in the DIY system get you MOST of the way there at a fraction of the cost.

(As an aside, Mark did a shootout against a commercial lens, and the DIY lens fared pretty well).

Anyway, I am sure my standards are a heck of a lot lower than yours. Personally, I don't really put all my faith in testing grids that demonstrate focus issues or CA. My standard is at the "movie watching" level. Once a movie starts, do I notice the slight focus issues or the slight CA? With the masking, do I notice the pincushion effects? Hardly. Am I pleased with the DIY lens? As punch.

Wow. Pretty high expectations for $100 anamorphic lens.

In fact if you could find the screen shots Sam posted, you could see the defocus at the edges...

Mark

You mention defocus due to CA toward the edges. I am planning to buy prisms for a diy constant width setup. I am using an IN72 480p unit to do the scaling. If the image resolution is increased by using all of the pixels, shouldnt the defocus be virtually undetectable from normal seating distances? As well as CA for that matter.

I get so confused reading all the post, one guy says he can live with CA and the other says he cant because it's so bad, yet they never tell the distnace they are making these judgements by. Is one guy looking at the screen within 12" and the other 12' ? I think every opinion should state setup, distance viewed, size of screen and equipment used. Of course a DIY lens will look better on a 1080p rs1 compared to a 480p in72. Just think it needs to be a little more structured comparison wise before you bash it or praise it.

A real big factor for the amount of CA in the image is the zoom setting of the projector lens. For the best results you need to position the projector as far from the screen as possible and set the projector lens to the smallest zoom setting. The less angle that the light leaves the projector lens the better.

Randy

A real big factor for the amount of CA in the image is the zoom setting of the projector lens. For the best results you need to position the projector as far from the screen as possible and set the projector lens to the smallest zoom setting. The less angle that the light leaves the projector lens the better.

Randy

Or if you can, calculate a pre-set TR - say 2.0:1 (screen height x 1.78 x distance from screen to projector). That way you know that CA will be reduced...

Mark

Hi Folks. I'm a new member with interests in anamorphic screening since I just acquired a Panny AE2000. I found this thread and was hoping for an easy way out with the prisms mentioned. I worked as a projectionist in my early days and used a couple of the high end prism based anamorphic add-ons for Cinemascope films (these went on the front of the main projection lens). These were simple coated prisms similar to what is being discussed in this thread BUT they were achromatic prisms. Each of the two prisms consisted of two slabs of glass cemented together (Crown and Flint) to correct for color dispersion, which may be largely responsible for the poorer performance some of you mentioned in this thread (sometimes what appears to be defocusing is really a color dispersion problem). Positioning of the prisms relative to the front element of the projection lens is also important to get the best results.

I started work designing a pair of cylindrical mirrors to accomplish the anamorphic squeeze or stretch (without the achromatic errors refractive elements introduce) but that is really only in the early planning stage right now. If I ever get on with that, will report my results. Just thought I'd mention the former though since non-color corrected prisms are famous for what they're used for - to disperse the colors in a light beam and make rainbows.

OMAN and the rest, sorry I have been away so long but my life has been in a bundle. I was rear ended in my postal vehicle and was off luckily a week then the holidays...I am still working on it and was sidetracked building my curved screen(which I love) SO I plan to get to my bud's place and see what he could do.

Thanks RBTO, looking forward to what you come up with.

T_Minton no worries, I'm still in the midst of construction and have also been working on a star panel for a skylight effect. These things always take longer or often get further sidetracked than we anticipate.

Is there any place to get DIY plans for an anamorphic lens? Just got my HC 4900 up and running and was thinking about giving it a try. Just doing zoom now and picture looks good to me. I would only imagine that a lens would make it that much better.

No actual plans available that I know of. If you want to try it out and see what the difference will be for you Surplus Shed is a good place to start for cost effective lens'.

Also see CAVX for a reasonable DIY venture with less DIY on your part.

All I can offer is the pics in this thread attached early on and descriptions of what I did early on when I got my prisms'. Hopefully soon I'll be able to get back into it.

Thanks Oman. How do you figure out what the angle of the prisms in relation to each other should be?

Go to post number 5, the fist image attached is a CAD drawing I believe, which someone from the french forum had done. What I did was print the image, and then reduced it to about 90% if I recall correctly, this allowed for it to be just about the same size of the actual prisms. I then cut it out and placed it within my enclosure to get the correct angles. They are pretty accurate but might still require a little tweaking. Also the lens assembly required some slight tilting to get a squared image.

If I recall here or I might have read it somewhere Mark (CAVX) suggests to basically project your 16:9 image and then place the lenses in front to expand it to 2:35 and basically one prism adjusts the left while the other adjusts the right. Of course you either need to have a 2:35 screen already or measure how big a screen you would get and mark off with tape. i.e. 90" wide <----> screen 90 X 1.33= 119.7. Likely rounding up to 120".

I went to "Surplus Shed" web site & found nothing when I searched for "French prism". Is there a part number or have stopped selling them ?

Thanks!

I went to "Surplus Shed" web site & found nothing when I searched for "French prism". Is there a part number or have stopped selling them ?

Thanks!

I think they call them something like "large anamorphic prisms pair".

I went to "Surplus Shed" web site & found nothing when I searched for "French prism". Is there a part number or have stopped selling them ?

Thanks!

Here's the link on their site.
http://www.surplusshed.com/pages/item/l9113d.html

These prisms seem to perform as well as any 2 prism based lens in most respects (and actually better than most in terms of focus).

But, the problem I'm noting is bad ghosting. This is easily seen with white text on a black background. For instance, the credits (like the "Hasbro" one) at the beginning of Transformers. This is the only aspect of these where their performance seems less than other two prisms systems.

Ghosting is caused by internal reflections and the angles of the prisms not great enough to move the ghosting off screen. It is true that these prisms operate at a much smaller angle than other two prism systems (which is why they can be so small).

I'm assuming this ghosting cannot be eliminated because it is a product of the angle of the prisms, but has anyone figured out anything I may have overlooked?

Thanks.

can anyone tell me what material is the corrective element made of? how thick should it be? and can one be made and put in a typical DIY 2 prism based anamorphic lens? or is it some special material that is too expensive to have for a DIY lens?

can anyone tell me what material is the corrective element made of? how thick should it be? and can one be made and put in a typical DIY 2 prism based anamorphic lens? or is it some special material that is too expensive to have for a DIY lens?

I'm assuming you are talking about the astigmatism correction element? If so, I've never seen anyone use one in DIY.

To me, the biggest issue with DIY is the CA. For that, you'll most likely need an achromatic prism pair. The common approach for this is crown and flint glass, but I've not seen anyone find a source for prisms of this nature. If we could this would be the "killer app" for DIY anamorphic.

Person99,

Thanks for your answer :-)

Yes you're right about the astigmatism correction element. CAVX is putting one in his upcoming Aussiemorphic III, so I figured why can't anyone put it too if one knows how to go about it :-)

I already have a BK7 prism pair for the lens, only want a corrective element now :-)

I'm assuming you are talking about the astigmatism correction element? If so, I've never seen anyone use one in DIY.

To me, the biggest issue with DIY is the CA. For that, you'll most likely need an achromatic prism pair. The common approach for this is crown and flint glass, but I've not seen anyone find a source for prisms of this nature. If we could this would be the "killer app" for DIY anamorphic.


As these too small ?

http://www.escoproducts.com/products/achromatic-lenses.php?show=1

As these too small ?

http://www.escoproducts.com/products/achromatic-lenses.php?show=1

Those are lenses. They cannot be used to create the optical stretch.

Well nothing ever came about with a metal enclosure, so now that my screen is ready I will be rebuilding my enclosure for my prisms. I already have some 1x6 lumber that I will be using this time around vs. 3/8th stuff I used before. The enclosure before was stable and all but driving the screws in to the side side panels and very close to the edges of the top and bottom pieces was causing cracking.

I will be using a similar design, but I just thought of a possible modification which will make for easy adjustment of the prisms if need be.

It seems that these French prisms are quite popular so I also ordered one pair. Still not arrived but I am trying to do an article about building it to the local magazine. I am trying to make it work in short throwing distance. I can report what is the working range with panasonic ax200 if anybody is interested. I have seen the great article about the other available trophies but not with this one. Let´s see how it goes.

It seems that these French prisms are quite popular so I also ordered one pair. Still not arrived but I am trying to do an article about building it to the local magazine. I am trying to make it work in short throwing distance. I can report what is the working range with panasonic ax200 if anybody is interested. I have seen the great article about the other available trophies but not with this one. Let´s see how it goes.

These are not bad--no image shift, very good on preserving focus, etc. They have one fatal flaw though. The angles used means that the reflected ghost image is on the screen and it is pretty bad with these.

These are not bad--no image shift, very good on preserving focus, etc. They have one fatal flaw though. The angles used means that the reflected ghost image is on the screen and it is pretty bad with these.

I was under the impression that these had an anti reflecting coating...

Mark

They do, I have not any reflection issues, nada, zip. Even putting the coated side of the prism directly into the projector's beam produced nothing but a shadow.

I just noted what you said about the lettering reflections Person99 in your earlier posts from May. We saw Indiana Jones this past weekend with the lens in place, and their were a couple fo scenes with lettering at the bottom of the screen at the beginning, neither my family members (my toughest critics) or I noted ghosting letters. Also we've watched some baseball and football and no problem with the tickers or score boxes. Tonight I wanna try and get some screen shots hopefully so I will try and look for that, even though I may not want to;) perhaps in closing credits.

In any event I made some progress on my updated enclosure. As I noted earlier an idea quickly came to me of how to easily access the lens to make quick adjustment and clean the lens' if need be. In the pics to follow you'll see how I'm doing this. I did re-use the corkboard from my last case as it is a good way to hold the lens' in place. I might still change that out for this padding you put in your kitchen drawers to hold holds things in place, but we'll see.

Here is a pic of all the material it is composed of
http://i240.photobucket.com/albums/ff231/oman321/Lens001.jpg
As you can see I already hinged the top cover
http://i240.photobucket.com/albums/ff231/oman321/Lens002.jpg
Then with everything put together
http://i240.photobucket.com/albums/ff231/oman321/Lens003.jpg
Open-says-me
http://i240.photobucket.com/albums/ff231/oman321/Lens004.jpg
Profile view
http://i240.photobucket.com/albums/ff231/oman321/Lens005.jpg
http://i240.photobucket.com/albums/ff231/oman321/Lens006.jpg
Latches attached, lens' in place for test closing
http://i240.photobucket.com/albums/ff231/oman321/Lens007.jpg
Success :D
http://i240.photobucket.com/albums/ff231/oman321/Lens008.jpg

For size reference I put a PS3 game next to it
http://i240.photobucket.com/albums/ff231/oman321/Lens009.jpg
http://i240.photobucket.com/albums/ff231/oman321/Lens010.jpg
http://i240.photobucket.com/albums/ff231/oman321/Lens011.jpg

In front of projector
http://i240.photobucket.com/albums/ff231/oman321/Lens012.jpg
http://i240.photobucket.com/albums/ff231/oman321/Lens013.jpg
http://i240.photobucket.com/albums/ff231/oman321/Lens015.jpg

It was at this point that I discovered because of the thickness the wood the prisms were being raised just a little bit to much so I had to cut it down. I basically sliced the bottom panel in half. It was a pain but I got it done, late though so that's why no screenie pics yet, hopefully tonight.
http://i240.photobucket.com/albums/ff231/oman321/Lens014.jpg
http://i240.photobucket.com/albums/ff231/oman321/Lens016.jpg

Need to sand that bottom panel a little more to smooth out the rough cut, lightly sand the hardware and spray the whole thing black for a finished look. I really like the hinged approach as it made it simple to be able to re-positon the prisms and then lock it down. This way I could also get quick access if need be to dust off the lens' from time to time.

Hi Oman321,

as i see, you use the same epson projector like me, which has no possibilty for vertical stretch. So my question, how do you stretch the image? HTPC? Or external video processor?

They do, I have not any reflection issues, nada, zip. Even putting the coated side of the prism directly into the projector's beam produced nothing but a shadow.

I just noted what you said about the lettering reflections Person99 in your earlier posts from May.

Even coated prisms will have some reflections (look inside the case and see the reflected image).

Couple of observations. If you have an LCD projector which has a poor panel CR, you might not see the ghost image that bad because either the black is too gray, or the white text is too dim. I see them on a PJ with a calibrated (tested) ANSI CR average of 650:1 and a peak ANSI CR of 900:1 with about 400 ANSI lumens. A dimmer projector or one with worse ANSI CR may not reveal the issue.

Secondly, after looking at your pictures, I can say that I've tested with the prisms much closer together (almost touching like Mark and others set up their lenses) whereas you have them spread out much more so the reflection may hit the inside of the case instead of bounce back out. I will try increasing the distance between the prisms to see if this eliminates the on screen reflection. I'll report back after some testing.

Widlarizer,

I got the discontinued Key-Digital 4x1HDMI (http://www.digitalconnection.com/products/video/kdhdmi4x1.asp) available at Digital Connection. I was able to get it at a slightly better price over what they are advertising it now for. Price has gone down, up, down, up recently so maybe wait a while if you decide you want it. It's great for a 720P projector and forum user ebr uses it with 1080P projector. The only down side is that it doesn't accept a 1080P signal(though it does output one) and it doesn't do 24fps.

Person99,

That would be cool if you could test that out. I have the Epson HC400 not calibrated and the manufacturer's specs say 5000:1 CR, 1500 ANSI Lumens. I know this is spec sheet ratings and not real world tested, calibrated, and properly setup numbers, it's just to let you know what I have and what the spec sheet says. Link (http://www.visualapex.com/Epson/Projector-Specifications.asp?For-The=PowerLite-HC400)

As far as the positioning of the prims, I was testing out my screen on friday and threw my old enclosure back together to align things. I first started with a print out of the schematic that I posted early on in the thread where the lens' do touch. I then needed to move the lens' in order to properly stretch the image to fill the screen. I then traced the result on the cork board that I was using for easy reference, that's just how they ended up being positioned. Maybe it resulted in an unrealized benefit, we'll see. Thanks for the feedback.

Person99,

That would be cool if you could test that out. I have the Epson HC400 not calibrated and the manufacturer's specs say 5000:1 CR, 1500 ANSI Lumens. I know this is spec sheet ratings and not real world tested, calibrated, and properly setup numbers

OK, if using it in one of the theater modes it is around 400 Lumens--so about what I've got. But, it has pretty elevated black levels, so you might not be able to see the ghosted image because your black level is so high (i.e. the "gray" or black is actually brighter than the ghosted image).

I'll see if the ghosted image is bright enough to snap a picture of.

As far as the positioning of the prisms, I was testing out my screen on friday and threw my old enclosure back together to align things. I first started with a print out of the schematic that I posted early on in the thread where the lens' do touch. I then needed to move the lens' in order to properly stretch the image to fill the screen. I then traced the result on the cork board that I was using for easy reference, that's just how they ended up being positioned. Maybe it resulted in an unrealized benefit, we'll see. Thanks for the feedback.

What gives the stretch is the angle between the prisms. You can get the same amount of stretch either with the prisms touching or if the prisms are 1" apart.

I got the discontinued Key-Digital 4x1HDMI (http://www.digitalconnection.com/products/video/kdhdmi4x1.asp) available at Digital Connection. I was able to get it at a slightly better price over what they are advertising it now for. Price has gone down, up, down, up recently so maybe wait a while if you decide you want it. It's great for a 720P projector and forum user ebr uses it with 1080P projector. The only down side is that it doesn't accept a 1080P signal(though it does output one) and it doesn't do 24fps.

If you are using it with a 720p projector (or any projector with a vert resolution up to 800), a used Lumagen DVI is a great processor. They can be had used for about $350.

In addition to the vertical stretch you'll get 11 point gamma adjustment, 4 calibration memories per input, the ability to input 1080p/24, the ability to output rates other than 50/60 Hz (if you have a PJ that accepts 48 or 72 as I do, this is great).

The biggest limitations of the DVI are no output above 800 vertical lines and no true film mode deinterlacing of 1080i (although I find 1080i film via it digital input seems to do pretty darn good most of the time with the component input being a bit weaker--but with 1080p/24 input you don't need a 1080i mode for blu ray).

For 1080p output or true film mode deinterlacing of 1080i or slightly better SD scaling, you need to step up to the Lumagen HDP which is going for around $750 used or $1000 new.

@oman321:
Thanks for your quick answer :)
I think, that it may be cheaper for me, to purchase a new projector including the vertical stretch, instead of searching for a key digital 4x1 video scaler here in germany ;)
But you're right, beside that, the Epson EMP TW 700 is a great home cinema projector :)
Do you have any test images of your DIY anamorphic lens?

@Person99:
Thanks for your advice :) I'll have a look where i could purchase an used Lumagen DVI here in europe...

I'll have to try the different modes tonight and see if I see anything.

Widlarizer, If I were shopping around I probably would certainly get a projector with the V-stretch built in. At the time when I bought mine it wasn't a prevalent feature for HD signals. I know the Panasonic AX100 featured it but I didn't like all the problems that projector was plagued with. Also the Key Digital does feature a horizontal squeeze mode which allows me to leave the lens in place and get a regular 16:9 image, although 16:9 stretched over a 2:35 hasn't seemed that bad either.

I don't have screen shots yet, I will hopefully be trying to capture some tonight.

Yeah, i already purchased the new Sanyo PLV Z700 which offers a built-in v-stretch.
But i still wanted to use my TW700 in the bedroom ;)

So I managed to get some screen shots yesterday. Word of warning, I don't have a tripod and I cannot set the white balance on my camera. I have a basic Nikon 4MP camera on which I turned off the flash and set the timer to take the picture. I tried propping the camera up on the back of my HT seats but it wasn't working out, so I had to hold the camera while sitting in the back row very still with both hands. Some came out better than others, some more crooked than others :p. As I'm sure most of you realize the images in real life look way better. Also reflection of the soffit area above the screen is also not an issue real life.

Indiana Jones: Spoiler alert if you haven't seen the movie

http://i240.photobucket.com/albums/ff231/oman321/screenies002.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies003.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies005.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies001.jpg

Star Wars III Revenge of the Sith
Lots of great scenes in this one, hard to choose so I gave them all to you:D
http://i240.photobucket.com/albums/ff231/oman321/screenies006.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies008.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies009.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies010.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies011.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies012.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies013.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies014.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies015.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies016.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies017.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies018.jpg

Over the Hedge, good movie.

http://i240.photobucket.com/albums/ff231/oman321/screenies019.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies020.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies021.jpg

This has got to be my favorite ;)
http://i240.photobucket.com/albums/ff231/oman321/screenies022.jpg
http://i240.photobucket.com/albums/ff231/oman321/screenies023.jpg

Person99, I was looking for the letter ghosting in different areas to no avail, including the Star Wars pics above. Then my wife and I decided to watch the most recent episode of Terminator:Sarah Connor Chronicles. After the show one of the logos that popped up on the screen was a black background with white lettering across and arched up in about 3/4's of the screen and what da you know, I saw some of the letter ghosting on the far right about 1/4 of the screen "curses". Anyhow I paused the image and started to investigate, what I discovered was that by placing my hand on the inside left side of my enclosure I was able to eliminate about 80% of the ghosting. I think by lining the inside of the case with velvet it will help to eliminate most if not all of the reflection issue. In any event the prisms are still a keeper for me, as this is still not an issue with subtitles with me.

The trophy prisms, HTB, and even the CAVX lens (no offense Mark) introduced reflection issues. I know of one person who picked up a CAVX lens second hand and was getting reflections shot back into and through out the room. Most issues were addressed by covering up the rear exposed section of the lens. For the money I am still quite pleased. I'll report back when I line the case and see if it thoroughly addresses the issues. Might be a couple of weeks though as I need to get back to work and finish the rest of my basement. Still looking foward to your results, perhaps the prism separation is taking care of some of the ghosting which is why I only got it in the far right.

Nice pics oman321 :)
Which throw ratio do you have in your home theater. I'm asking because i would like to know how much pincushion do you get with these prisms?

My projector is about 14' away from the screen so 168". If I understand it correctly I'm supposed to calculate the width of my 16:9 screen which would normally be 82.5". So 168/82.5 = 2.03 throw ratio?

My screen goes in about 3" from the edges. I got an excel calculation sheet from Aussie Bob which helped to figure how much curve I needed. Without the lens in place you can see that the edges of the image (about 6" in) don't quite make it down to the screen bottom. with lens in Place the edges make it all the way down.

Ok, 2.03 throw ratio sounds good and i've forgotten, that you have a curved screen :)
Well...nice setup. I wish i could build a curved screen for my homecinema...but it seems quite difficult for me :(

Not as tough as you may think, I was a little nervous about it at first, but now that I've done it, it was quite easy. It kind'of depends if you are putting a curved screen on a false wall which is also curved like me or if you are putting a curved screen on a flat wall like tr6 (someone else who built a curved screen like me), his screen build (http://www.avsforum.com/avs-vb/showthread.php?t=933667). You can check pics of my screen build in my construction thread linked below in my signature line.

About the enclosure. I founded out that the felt stickers for furniture legs are quite good to "eat" the light (black and brown ones). You can find these in your superstores quite easily. They will sell those small circle ones (which are useless) and also A4 size. Many have just painted the inside but it still reflects the light (not much but still a little). It will also covers your prism if you want to move those (pass through and stretch options).

Thanks for the tip myky I will keep that in mind. Right now I plan to use some left over velvet that I have from my screen border. It does a great job at sucking up light. The lens I plan to leave in place all the time in wide mode. My scaler does provide a horizontal squeeze mode for 16:9, but I gotta say my 16:9 doesn't seem bad at all stretched to 2:35. Until I get some sort of masking in place I may just view it that way.

I have my new enclosure all spray painted and looking good in black. I also lined the inside with my left over velvet, to cut down the letter reflections which also makes it look very nice.:cool:

I went to snap off some pics to show it here and my batteries are dead... :( I'll try to post some pics soon.

BTW, I tried to observe if the letter ghosting would still be an issue and they appear to be about 98% or more taken care of. That's good enough for me.

Person99, I was looking for the letter ghosting in different areas to no avail, including the Star Wars pics above. Then my wife and I decided to watch the most recent episode of Terminator:Sarah Connor Chronicles. After the show one of the logos that popped up on the screen was a black background with white lettering across and arched up in about 3/4's of the screen and what da you know, I saw some of the letter ghosting on the far right about 1/4 of the screen "curses".

Yep. That is where it is. I did some testing this weekend and could not eliminate the ghost images in any way with these prisms. It is on the same side of the screen as the front prisms "thick" end.

Anyhow I paused the image and started to investigate, what I discovered was that by placing my hand on the inside left side of my enclosure I was able to eliminate about 80% of the ghosting. I think by lining the inside of the case with velvet it will help to eliminate most if not all of the reflection issue.

This may help, but I've tried triple black velvet in the case and to ensure that it was a case problem I tried them without a case (so there is an almost infinite case). In all cases (no pun intended) there was a ghost image--i.e. nothing eliminated it.

The trophy prisms, HTB, and even the CAVX lens (no offense Mark) introduced reflection issues. I know of one person who picked up a CAVX lens second hand and was getting reflections shot back into and through out the room. Most issues were addressed by covering up the rear exposed section of the lens.

As an FYI I also have an Aussiemorphic Mk II and the current HTB lens at my house that I've also tested. You are correct that all of the low cost prism based lenses have reflection issues. Most can be treated as you noted or left unchecked (a reflection on the back wall does not disturb the movie at all).

But, here is the CRITICAL point. Neither the Aussiemorphic nor the HTB introduce reflections that are on the screen. In other words, though they may have reflections, they don't make ghost images on the screen. I'll take a mini-screen image on the back wall over a ghosted image anytime.


Still looking foward to your results, perhaps the prism separation is taking care of some of the ghosting which is why I only got it in the far right.

Nope. The results are above. Ghosting is always on the side with the thick edge of the front prism. Honestly, given the intensity of the ghosted image, I think you are not seeing it as much because of your PJs elevated black levels (no offense intended). I have some neighbors with PJs that have elevated black levels like yours, so I may try to test on theirs to see if my theory holds true. I think that black on your PJ is gray enough that it is actually brighter than the ghosted image most of the time. If this is true, then these prism are probably fine with projectors that have high black levels such as LCD projectors, pre-DC3 DLPs, and the old (1400x788) JVC LCoS machines. I think on projectors with a calibrated on off contrast ratio of under 1500:1 (so a rated on/off of about 3000:1 or less) these will work, on higher CR projectors they will not.

Just as an FYI, all my testing thus far has been done with a PJ that measures (not specced) as follows:
Average ANSI CR: 647:1
Peak ANSI CR: 890:1
On/Off CR: ~2800:1

Person99,

Thanks for the feedback and taking the time to do some more testing. As it stands now it seems to me that the velvet has helped with most of my issues, although I only had a chance to quickly check it and it would be worthwhile for me to continue and try to observe if the ghosting problem is persistent. I can also try putting the projector in different modes i.e. theater mode, theater 1 or 2 and see if this makes a difference with black levels and makes the ghosting more apparent.

Let me ask, since you have an MkII and a HTB lens, you wanna give me one, :p jk. Actual question, they basically use trophy prisms correct? The MkII might uses special ordered Bk7 lens' but I'm not sure. So with these no ghosting problems, but on the versions that you have are they coated on the sides and top and bottom if they were standing up? If I get some trophy prisms am I gonna have issues on screen because of the lack of AR coating? I suppose they could be lined with something to eliminate the issue.

If I were to do this I would probably go with the small ones as I would need to get the lens to fit inside a projector shelf/soffit. Seeing how these are so small I would hope the small trophy prisms would be ok also. In any event for the time being I'll hopefully be ok, if the ghosting does become an issue the trophy prisms would be worth investigating for my needs, as they are the alternative that would best fit my budget.

Also a small picture reflected back wouldn't be a big deal for me as the projector will eventually be enclosed, with only a port for the image to shine thru.

Do not worry about the ghost image. All trophies that people are using for anamorphic lenses will have ghost image. So do not jump from one ghost image to another

Please read the great article about the DIY anamorphic lens (award plaques). Read specially the section "Reflections".

It just happens if you do not have good anti reflection coating. I believe that the French prisms are only coated from the sides, but how about the actual "lens" part? Anyway you will not get rid of the ghost image unless you will order your prisms from optic company or something (which will make the real AR coating and that means a special layer(s) to the surface of the lens where the light hits).

If you really want to see your trophies or normal prisms performance watch one of the James Bond beginnings and voila! You will see it.

If you do not see it, please tell us how did you get rid off it :)

Thanks myky,

I wouldn't be jumping anytime soon, the wife would have my head as I have given to much time to this project. Your right about the prisms only being coated on the sides, I also believe the other prisms in question are also coated only on the sides.

Do you have a link to the article? I'll have to check out a bond movie and see how it does.

Hmmm it seems that I forgot to actually give the link in the previous mail. Here it is: http://www.zuggsoft.com/theater/prism.htm

Thanks for the link.

Here are some pics of my finished enclosure. It's as finished as it needs to be since the shelf you see it sitting on in front of the projector will be enclosed and their will simply be a port hole (square) for the image to shine thru.

http://i240.photobucket.com/albums/ff231/oman321/Lens023.jpg
http://i240.photobucket.com/albums/ff231/oman321/Lens022.jpg
http://i240.photobucket.com/albums/ff231/oman321/Lens021.jpg
http://i240.photobucket.com/albums/ff231/oman321/Lens025.jpg

On the shelf
http://i240.photobucket.com/albums/ff231/oman321/Lens020.jpg
http://i240.photobucket.com/albums/ff231/oman321/Lens019.jpg
http://i240.photobucket.com/albums/ff231/oman321/Lens018.jpg
http://i240.photobucket.com/albums/ff231/oman321/Lens026.jpg

Like I stated earlier the inside was lined with velvet and it looks better in person since the flash brings out imperfections which aren't normally seen.

Just checked that out myky,

I had seen that before, but never read the whole thing thru, nice to know. Still very affordable solutions for us DIY'ers.

I have still not got the prisms. Waiting is futile so I already started building my enclosure. I have made two prototypes. One is like oman321 has and one is smaller. I will add to the box the fine tuning trimmers so that I can easily modify the lens angle.

I am about to drill the holes but I do not know the size of the small prism.
Is it like this:

I confirmed that the bottom of the prism is 1.20 inch wide (30,5mm) and it is 2.755 inch (70mm) high.
But are the two longest sides about 3.464 inch long (88mm)?

The reason to confuse my mind is that in this thread there was pictures were the two longest sides were only 3.346 inch long (85mm).

So which to believe?

Anyway I will send photos about the project soon :)

Hmm. not sure the website says 88mm
http://www.surplusshed.com/pages/item/l9113d.html
but the pics I have say 85mm.

I will try and check for you when I have a chance but likely not till tomorrow night.

Also I had called surplus shed a few weeks ago to see if they were still producing them and they said they were but they are waiting for them to come in. I guess they have a delay of some sort.

Please do post pics when you have time.

What are the angles of the prisms that are used for DIY lenses?

Different prisms have different angles, I believe these have like a 20 degree angle.

The angle is 20. Hmmm... I forgot that. You can calculate it.
If the bottom is 30,5mm and the half of that is 15,25. Then the angles are 10, 90 and 80 (total has to be 180). So then we shall use following math:
X = tan80 * 15.25 = 86.48mm

Well it seems that it is between those two values what we have seen.
I need to calculate the bottom again to get the real value.

I calculated the wrong side. The hight is 86.48mm and if the bottom is 15.25 then the longest side is then 88mm :)

It is long time since I have use trigonometry but I managed to get it right.

Hi!
Finally I managed to snap few pictures of the enclosure. Still waiting the prisms, but everything else is ready. You can see also the mounting solution.
Give feedback :)
It is quite small and does not look so ugly as I thought.

http://s463.photobucket.com/albums/qq355/myky_1/

Looks great myky,

I had sketched and contemplated going with an angled design like that, but when I decided to make it hinged and because it was such a small enclosure already I decided to just go with what I have.

Your case looks very professional, you really did a great job. I know you had mentioned making it so you could adjust the prisms and I suppose that's what the 2 butterfly nuts on top are for. Is this how you also plan to access the enclosure once you get the prisms? Must be killing ya not having the prisms yet, any ETA on them?

Yeah it is pain to wait :) But then again I had time to think and finalize the enlosure. The best estimate is 3 weeks. So it will go to early next year.

The butterfly nots are the "trimmers". I have 2 nots more for the bottom (not installed yet). I will glue those to prisms and that is it. The top of the enlosure is open so if I want to clean up the prisms, I just open the butterfly nots and open the hatch.

It took longer to design the mount solution :)

Hi myky,

the enclosure looks really nice :) Did you use MDF boards to realize this and painted the insides black?

The real hifi-people are going to laugh at me.......I used particle board!
The only thing I used that was because you can buy it smaller sizes.
You have to buy the whole board 220cm*140cm if you want the MDF(in Finland).

It was real pain to work with. All the edges were damaged and I had to use the putty (filler) to cover up those.

The inside of the enclosure is normal felt sticker what you usually put under the chairs. Eats the light and is soft enough to cover the prisms.

You have to buy the whole board 220cm*140cm if you want the MDF(in Finland).
It's the same thing like here in germany. I also would have to buy a whole plate, although i don't need most of the material.
So i've asked several local cabinet makers if they could build such an enclosure for me. I'm still waiting for the response of one of them, who had 16mm black colored MDF boards.

The idea to use the felt stickers sounds good and it seems to work nice :)

Do not worry about the ghost image. All trophies that people are using for anamorphic lenses will have ghost image. So do not jump from one ghost image to another

Please read the great article about the DIY anamorphic lens (award plaques). Read specially the section "Reflections".

It just happens if you do not have good anti reflection coating. I believe that the French prisms are only coated from the sides, but how about the actual "lens" part? Anyway you will not get rid of the ghost image unless you will order your prisms from optic company or something (which will make the real AR coating and that means a special layer(s) to the surface of the lens where the light hits).

Personally I found the ghosting intolerable. I tried the HTB and CAVX lenses and their preformance was comparable to these prisms--but no ghosting! Frankly, the ghosting is so bad it is completely unacceptable. I don't think a few hundred bucks more is too much to pay for a markedly better image.

Hmmm... I have heard that in here (Finland) people have managed to get rid of the ghost image with fine tuning the prisms angles.
It might be that they do not see it or something. As you mentioned earlier that the projector plays one part in this (contrast ratio).
Anyway I will get into this when I get my prisms. If there is a way to get rid of the ghost image (or reduce it heavily), you will be first to know.

Do you still have the prisms?

Hmmm... I have heard that in here (Finland) people have managed to get rid of the ghost image with fine tuning the prisms angles.
It might be that they do not see it or something. As you mentioned earlier that the projector plays one part in this (contrast ratio).
Anyway I will get into this when I get my prisms. If there is a way to get rid of the ghost image (or reduce it heavily), you will be first to know.

Do you still have the prisms?

Yes, I still have the prisms.

I've tried fine tuning them ad infinitum. But good luck and hopefully you'll figure something out.

I think reflection also is effected by the internal angles of the prisms. If you look at the angle the prisms are placed at with regard to each other, on Mark's CAVX lens or the HTB lens, it is quite a bit larger than the angles at which the these lenses get placed at, so the internally generated reflection get reflected out of the back of the lens to the back or side wall instead of a portion being reflected back to the screen as a ghost image.

Just wondering that if you want to get rid of the prisms I would be interested of buying them :) I have been waiting the new prisms since 17.10.2008.

If they are OK and no scrathes on them give me a prize to work with :)

I think reflection also is effected by the internal angles of the prisms. If you look at the angle the prisms are placed at with regard to each other, on Mark's CAVX lens or the HTB lens, it is quite a bit larger than the angles at which the these lenses get placed at, so the internally generated reflection get reflected out of the back of the lens to the back or side wall instead of a portion being reflected back to the screen as a ghost image.

The CAVX MKII used 15 degree prisms where these "french" prisms are 20 degrees. You should therefore find that the displacement (angles required to produce anamorphic stretch) should be less, not more.

Even though these prisms are coated, you will still get some reflections on the side walls due to the fact that the prisms faces are flat. Ghosting on screen is an aligment issue, but also may be due to the TR where the further back you can mount the projector, the better.

Mark

The CAVX MKII used 15 degree prisms where these "french" prisms are 20 degrees. You should therefore find that the displacement (angles required to produce anamorphic stretch) should be less, not more.

Yes, that is what I said, sorry if I didn't communicate correctly.

Even though these prisms are coated, you will still get some reflections on the side walls due to the fact that the prisms faces are flat. Ghosting on screen is an aligment issue, but also may be due to the TR where the further back you can mount the projector, the better.

Mark

Yes, they all do that. My point was, yours do not put a ghosted image on the screen. HTB lens does not put a ghosted image on the screen.

I have tried every alignment you can imagine with the "French" prisms. At TRs up to 1.7 (my current PJ does not go higher than that), there is a ghosted image on the same side of the screen as the screen side prisms "fat" end. On the stretched picture, if credits are rolling up the center, then the ghosted image be at the edge of the screen. You will see about 60% of the credits (the other 40% are "off the screen").

If I feel like it, I'll try them with a friends projector at a 2.0 throw and see if the ghosting goes away.

The French prisms are two different sizes unlike yours or the HTB--one must be the "back" and one must be the "front". Further, the "front" prisms "short" side (i.e. fat edge) is not like yours and the HTB. The "front" prism of the "French" prisms is NOT an isosceles triangle like yours or the HTB. The front side of the front prisms is longer than the back. This means the "base" of the prisms is at a vastly different angle relative to the light path and screen that yours. I think the ghosted image is being reflected off that edge and to the screen as the angles look correct for that. I've tried every opaque thing I could to coat the edges and nothing stopped that reflection. I have to wonder if that front prisms was an isosceles triangle, would there be no reflection?

Just wondering that if you want to get rid of the prisms I would be interested of buying them :) I have been waiting the new prisms since 17.10.2008.

If they are OK and no scrathes on them give me a prize to work with :)

Hyvää huomenta, too bad I'm not going to Finland every 2 months like I used to, I might have been able to drop them off.

Let me see if I can try them at a 2.0 throw at a friends to see if he wants them (assuming they don't ghost at that throw). If he doesn't want them then I have not use for them and my wife is hounding me to get rid of much of the stuff I don't use!

wow wow wow. very good

Person99 how did it go with the prisms?
I have still have not got the prisms, but one thing is sure and that is they will not arrive for me this year :)
Happy new year and prisms!

Just got the prisms and they are working like trains toilet (cruel but works).

First findings:
-Picture quality ok (good sharpness)
-a little ghost image, but only can be seen in beginning of james bond :) Nothing with other material.
-can be used in very, very short projector distance. projector is 3m from the screen and with these prisms you can get 282cm wide and 120cm high image without any problems.
-a little smutty from the edges if you look computer test screen, but in movie you cannot see it.

What can I say. Best project I have ever done. Money to the bank I say!!!
I have seen Prismasonic's best product in action and I can say that this one does not loose too much. Of cource there is difference, but this is good product.

I will post few images soon.

I have seen Prismasonic's best product in action and I can say that this one does not loose too much.

All I can say is I disagree COMPLETELY with this. Either you really have low standards or you have only done a very cursory look at these. The ghosting on these is REALLY bad. The better the CR of your PJ, the more visible this ghosting is.

Prismasonics best does not have the ghosting, the color fringing, or any of the problems of these. Honestly, it is well worth the money to step up at least to the CAVX or HTB lens (I've compared all of them). You get even more bang stepping up from that.

I watch the movie and not the defects :) No really, I know what you are saying and this product is not for all projectors. I am nearly saying from my point of view (Panasonic AX200, less than 6000:1 contrast ratio).

And I have quite high standards when it comes to the picture (e.g. see my posts about the rainbow effect in the backlight lit LCD TV).
I have really tried to get the ghost image to pop-up to my eyes, but james bond is the only one. At least with my projector. It is so faint the I can babrely see it. It was quite an effor to take a photo off it.

For those who own better projectors WILL not like the image. I am writing an article about the whole project to dedicated magazine, so trust me I know what I am talking about.

And yes the prismasonic has 0 problems and so on (seen it in action more than one second).

I was about to order the bigger awards prisms, but then I managed to see few photos of the real size and they were really too big. I mean you have to be quite an artist to create a nice box out of those.
I knew that with small and quite good looking box I will get also ghosting.

I will post one ghost image and you will see how faint it is with ax200.

More details about the whole project:

The ghost image is there and you can see it in every scene where there is bright white object on black background. This means every start/end credits or very rare night scenes (watched the sin city without problems).
With higher contrast projectors it is an issue!!!

But here is for those who has ability to move your projectors:

I measured the size of the picture when the ghost image will sift to right so much that it can be removed totally with masking.
Details are: from 3m distance you need to project 62cm high and 146 wide image and they go over the screen. Of cource you need to finetune the prisms and stuff, but it works. You can now calculated your own distance from the screen and do the math.

The ghost image will become clearer with playing your projector zoom.
Look e.g. MIRAMAX logo. I can see the ghost image on right hand side (all depends which side your front prism is open, left or right). How close it is with the real logo, depends your zoom level and angle of the prisms.
So let me make clear. It is totally ghost free in the projected image with one precise setup. All others need to "suffer" it. For my projector it is not a problem. I will anyhow ignore at least the end credits, unless there is some joke coming up or some movie misstakes.

I could see the ghost image from ax200 with dynamic mode and only in the start/end credits or bond. With lamp mode cinema I had to really watch it.

So I really, really recommend these prisms to all the DIY people IF you have projector what is "bad" enough :)

When you really watch the movie you cannot see it. My earlier projector (panasonic ae300) had 2 dead pixels and I could see those from 4.5m away and the screen was only 200m wide and 114cm high. The knowing of the problem makes it worse. You will start to look that from every frame you can see. Same thing in the LCD TVs where you can see the rainbow problem.

This sounds like "Yes we can!" speech, but really the point is clear. Ghost is there permanently(except one setup), but you can live with it if you have low end projector and finetune the system enough.

Sorry about the long reply!

Sincerely
Myky

myky, glad to hear you finally got your prisms. I was feeling bad for you. Yes there is some ghosting. My ghosting was greatly improved when I lined the inside of the lens case with velvet. I can barely see it like you said when there is a black background and white lettering. Terminator the Sarah Connors Chronicles has a "BARTLEBY" logo at the end where I see it to the right of the logo. I don't see it with subtitles, which is where it would really bother me. $125.00 vs. $600.00 is simply to great a difference for a very marginal improvement from all the reviews I have read.

I really don't have color fringing issues, I can see color fringe or CA at the very edge of the left side of the image which is simply taken care of with just slightly shooting the edge image on to the velvet border.

Overall my image is very pleasing and if I remove the lens the image without the lens is very comparable.

While I know screen shots can't do a projected image justice, this is one of my favorite screen pics which I have taken with the lens because of the fact that it shows a real world movie image with a grid. No ghosting, color fringe, simply a great picture and all who have seen in person agree.
http://i240.photobucket.com/albums/ff231/oman321/DSCN2647.jpg

Good morning! Here is the ghost coming to you via overexposure picture with camera and then the normal viewing image.
I do not have yet the 2.39:1 screen so image has projected to old 16:9 screen (this way the prisms can be fine tuned easily to correct hight and lenght :) )

Hey myky,

Now that you have had your lens' for a couple of days how are you enjoying them and the new picture?

I watched Slum Dog Millonaire last night with the Mrs. good movie. It had some very dark scenes especially when the main character was in the hot seat. I had no ghosting issues with the contest questions and answers which were being shown on the bottom of the screen.

The only time I noticed a brief and I mean very brief shadow/ghost image was from Jamal's face on the far left side of the screen above the questions and the rest of the screen being black. Out of the corner of my eye I could almost see very briefly a shadow but when I tried to look or focus on it I couldn't really see it.

Also since I have an AT screen with no lining behind it, it could be an issue with the reflection coming off my back wall. I'll be lining that back wall in the near future so if it that is the issue it will be addressed. Even so the image and the detail for me has been excellent. Hope your enjoying the new set up.

All I can say is that I enjoy every second of it :)

As I meantioned earlier post that I have quite a eagle eye so I will spot the ghost image in e.g Star Wars yesterday. The lightsaver is so bright that if you know the place where ghost image is going to be you will see it. Even in moderate light scene. Of course I reduced it by setting the projector settings to cinema instead of vivid cinema. Just used that setting for pictures.
Normally in dark room I use the cinema settings and the ghost image is not visible. If you have dim light on in your room, it will be even harder to spot it.

Yesterday I also finished my article for the local magazine (26 pages total, DIY anamorphic lens). Plenty of pictures, pros and cons etc..
I had 6 months time to thing the tests and stuff so it turned out to be quite an huge article. Hopefully some of the material can be published in here, but I need to wait the permission for that. In the meanwhile I can post few extra photos I took.

I would love to check out the article and your photos. If you want to learn how to post photos right to your post like I did in the last post of page 7, check out this link.

http://www.avsforum.com/avs-vb/showthread.php?t=1122305

Thanks, that is usefull.
I will one way or another publish the article for you guys, but before that I need to discuss with the magazine producer. I am not sure can I publish my stuff in here until it has been releases on the magazine.

Anyway I think that it is going to be soon. I also need to start translating it to english, unless you can read finnish :)
I also need to find a way to split it. With the original pictures the article is 56Mb and with the reduced resolution about 10Mb.
Still it is too heavy for here. I need to put it somewhere where all can read it and see the pictures clearly.

Here are few pictures I promised. One is from pirates of the....
and the second one is taken from right corner of the test pattern (white lines and the CA).

Sounds good looking foward to it.

Seems like a lot more CA over what I see on my test grid. I'll have to see if I can take a shot of it this coming weekend and post for comparison.

About the test grid:

The grid was taken from the star wars dvd. There is the THX test grid.
The down side is that it is only in 4:3 format. I had to zoom to image to fill up the whole 2.39:1 area. This means the grid was quite thick already and it is quite smutty. I did not have any other ways to get the test grid.
So it might be that it had some impact to the CA. Anyway you can see it quite clearly. Here is the test grid.

Hi, sorry for dig this thread up. i just got my french prism and found this chip on the bigger one. I'm so worried that it will effect the picture (my ordered projector didn't arrived yet). Do you guys think this chip would effect the picture :(

http://img58.imageshack.us/img58/2750/prismchip01.jpg

I`m glad somebody dig this thread up, because i have also a question about these prisms.

I`ve understood that if you black out edges of those prisms, it will help a bit with reflections (and maybe with that ghost image also?).

So wich edges can be blacked out/paint black? Obviously those side edges, but how about that end part?

Does anyone has any experiences how much this will reduce reflections?

First to the hellvy:

I made a misstake with glue and I have it in the same spot as you have your scratch. It do not affect to the picture quality.
The image will not be so big when it leaves from the last prism. So do not worry.

Then Donhou: I will try also to make some kind of painting or cover to the sides. I am not sure does it have any impact, but I think it does not make it worse. I think that the majour problem is in the prisms. The AR coating should be on the path of the light and not on the sides.

Hi, sorry for dig this thread up. i just got my french prism and found this chip on the bigger one. I'm so worried that it will effect the picture (my ordered projector didn't arrived yet). Do you guys think this chip would effect the picture :(

http://img58.imageshack.us/img58/2750/prismchip01.jpg

If your projectors beam hits that chip, you will have vignetting issues long before you see an indication on screen from that chip.

I`m glad somebody dig this thread up, because i have also a question about these prisms.

I`ve understood that if you black out edges of those prisms, it will help a bit with reflections (and maybe with that ghost image also?).

So wich edges can be blacked out/paint black? Obviously those side edges, but how about that end part?

Does anyone has any experiences how much this will reduce reflections?

First to the hellvy:

Then Donhou: I will try also to make some kind of painting or cover to the sides. I am not sure does it have any impact, but I think it does not make it worse. I think that the majour problem is in the prisms. The AR coating should be on the path of the light and not on the sides.


I found that their really is no need to paint or mask the sides of the prisms. When I first got them I placed them in front of the light path to see how much if any reflections were coming from the sides which are AR treated. Absolutely no light or image came thru.

The reflection which you may be seeing is because of the shape of the prisms themselves as myky states. I believe their is an internal reflection which you can't really do anything about. You get the same issue with trophy prisms but sometimes you are able to project it off the screen or so I have read.

The thing I did which helped tame the reflection was to line the enclosure with velvet and since I have an AT screen I was also getting some reflection from behind my screen wall, only seen during all black scenes with white lettering. Since placing speaker cloth behind my screen I have not seen the reflection again. Your results may vary as I know contrast ratios of individual projectors will factor into this.

First to the hellvy:
I made a misstake with glue and I have it in the same spot as you have your scratch. It do not affect to the picture quality.
The image will not be so big when it leaves from the last prism. So do not worry.
If your projectors beam hits that chip, you will have vignetting issues long before you see an indication on screen from that chip.

Wow, what a relief. Thank you for the answers :D

hellvy - you said you have a "bigger" prism? I thought the French prisms were all one size? And can you tell me what size these bigger prisms are?

hellvy - you said you have a "bigger" prism? I thought the French prisms were all one size? And can you tell me what size these bigger prisms are?

I think he meant the bigger of the two prisms which came in the package. They are the same as the Surplushed offering which consist of the two prisms which unfortunately for us are too small. I checked again with Surplushed yesterday and was told they still do not offer anything bigger. :(

I wanted to add these pics because they illustrates how to a create case which allows for a passthrough mode with dimensions. Again I don't take credit for any of these they are pics from the French site. Thanks goes to them they've done a lot of hard work.

Hello,
Which image represents the proper sizes:
epure_06_03_04.jpg
plan1.jpg

They seems to be slightly different..
Thanks,
Wojtek

I am not certain if the printed image from post 8 represents the proper size or if the measurements are accurate. When I posted the images in that post I figured it was pretty good for reference because it had measurements listed on it.

The other image which I printed in order to figure out how to best align the prisms is from post 5. I had to reduce it by 10% I believe to make the printed image of the prisms the same size of the actual prisms.

Hope that helps.

I am not certain if the printed image from post 8 represents the proper size or if the measurements are accurate. When I posted the images in that post I figured it was pretty good for reference because it had measurements listed on it.

The other image which I printed in order to figure out how to best align the prisms is from post 5. I had to reduce it by 10% I believe to make the printed image of the prisms the same size of the actual prisms.

Hope that helps.
Great, thank you. I am planning to start working on it this afternoon. I just hope that the prisms are big enough for Optoma HD20...
Thanks,
Wojtek

Good luck. Test it out 1st, if you have the prisms already. The 1st prism can go just about against the projectors lens.

Just to confirm I went back in the thread to see if it was 10% which I reduced the image by. It was, I posted about it back on post 48.

Hello, i've tried french prism for a while. There's 1 issue i'd like to ask. On my set up i got uneven CA for left and right side of the screen. The left got noticeably more blurry and more CA than the right side. Is it normal that way? Or it should even in CA and sharpness? Is there any thing i should check it out?

Sorry for no pictures. I'll shoot and post it when i get home, thx.

I haven't looked for it for a while, but I only easily see CA at the very edge of each side of the picture. I simply overscan ever so slightly onto the border and has been a non issue. I can look at it a little better this weekend with a grid to see if I notice any focus issues, but to be honest the focus has always seemed fine to me.

Hi, sorry for late images. Here' re what i've got so far. Is this uneven ca and focus normal? Or i should tweak something to get better result?

left side
http://img262.imageshack.us/img262/7237/dsc00688mod.jpg

right side
http://img406.imageshack.us/img406/7554/dsc00687mod.jpg

That is an alignment issue. The CA should be symmetrical, so either the prisms are not set up correctly or your projector is not 100% centered.

Ya, that is definately off??? I have never seen anything like that when I throw up a grid. If I get a chance I will try to snap some pics tonight and show you what mine looks like.

I had the same issue with my lens.

Really? If it is in fact the lens I can imagine there is anything you can do to resolve it. I know you were pretty pleased with your results so is it only evident with a test grid?

Edit, I saw our discussion a few posts back Myky its been a while so I didn't recall it.

Are you having the same effect as hellvy though, where one side has a lot of CA and one side looks pretty good? Something just doesn't seem right.

Yes I have more CA in the left side of the image. But it is all about the lens shift and how you turn your projector.
To get equal CA to both sides you need to center the lens shift function, or use it as little as possible(I have panasonic AX-200). Then you need to turn the projector a little to the worst side of the CA (in this case left). With this trick you can get the picture to look ok in CA point of view.

But if you do not use the lens shift at all or turn the projector too much then the image itself is getting too much pincussion.

So if you do not have a possibility to move your projector then you need to do these tricks to get the image Ok.

Guys, a quick tip. The angles of both of these prisms are 20 degrees. You need to start with the one of the edges of each of the prisms parrallel to each other (opposing apex) which constitutes a "bi-pass" or no stretch mode. You should also ensure that your projector is perpendicular to the screen as attempting to re-aligne the projector after you displace the prisms will only lead to frustration and non uniform stretch and CA.

Once you have the projector centred, you can then rotate the prisms to get your optical stretch. You also need a 2.37:1 screen or markers as you need to be able to find the limits of the prism displacement to obtain the correct 1.33x.

Thanks for the insight CAVX. This is perhaps why I have not seen an issue as I adjusted everything very similar in the manner which you describe. Projecter centered first, with no lens shift left or right. Then lens' adjusted accordingly.

No chance to get any pics last night, hopefully tonight.

Thank you CAVX for very information. This issue should came from my noob and unprofessional set up. I'll try to re-align from ground up again :p

I got a chance last night to throw up some test grids and low and behold I do have a fair amount of CA on the left side of the screen :o.
Now that I think about it I have always gravitated to the right side of the screen when looking for issues close up.

Anyhow I would say that it didn't seem as bad as hellvy's but somewhat how myky looks in his pic posted a while back. My scaler offer a couple of different modes and color ramps so I got some shot of most of them.

Single line shot
Left Side:
http://img402.imageshack.us/img402/6660/dsc01238m.jpg
Right Side:
http://img204.imageshack.us/img204/8656/dsc01240.jpg

Grid
Left Side:
http://img204.imageshack.us/img204/7458/dsc01241l.jpg
Right Side:
http://img84.imageshack.us/img84/1006/dsc01242a.jpg

Color ramp: I couldn't see any CA in this test pattern but I thought I would show how it transitions from white.
Left Side:
http://img402.imageshack.us/img402/1846/dsc01243j.jpg
Right Side:
http://img262.imageshack.us/img262/5872/dsc01244r.jpg

White square black background:
Left side:
http://img231.imageshack.us/img231/2782/dsc01245ly.jpg
Right side:
http://img262.imageshack.us/img262/4162/dsc01247h.jpg

This is an alignment grid from the projector and CA was not evident here either.
Left side:
http://img204.imageshack.us/img204/7619/dsc01251j.jpg
Right side:
http://img222.imageshack.us/img222/1302/dsc01250m.jpg

Test grid again going from left middle right
http://img504.imageshack.us/slideshow/player.php?id=img504/4871/1257357539yx1.smil

The best I can do with Imageshack is link to the slideshow. When my photos get restored in photobucket I will add the above slideshow from there to this post.

oman, can you either upgrade to pro today - or upload to imageshack.us?

;)

No plans on upgrading, but I will try to move over to imageshack if I get some time today, if not I should be able to give it a whirl tomorrow.

Just for you elmalloc I have moved the pics over to imageshack. Gotta say though their interface and useability sucks... Still working on the last 3 pics, I am trying to make it a slideshow.

Hi, i'm back from (roughly) re-align my projector. I found that it was misalign from my diy lens mount installation. Here's result after put it back as good as i can.

projector test grid, project on existing screen (notice 2 vertical bars)
http://img256.imageshack.us/img256/6540/01dsc00715mod.jpg

left grid
http://img25.imageshack.us/img25/2492/02dsc00713mod.jpg

right grid
http://img25.imageshack.us/img25/1699/03dsc00714mod.jpg

test pattern
http://img256.imageshack.us/img256/3060/06dsc00719mod.jpg

left side
http://img25.imageshack.us/img25/3584/04dsc00716mod.jpg

right side
http://img442.imageshack.us/img442/8056/05dsc00717mod.jpg

Even though the picture looks like the left CA side is not getting better (or worse than my before projector aligning) But in real life i can tell it's better. On the right side i can see less CA but more than before aligning.

ps. I use almost max projector zoom to archive my desired screen size. So the CA and image distortion may look bad. But i'm fine with it. I want to use less zoom but my ceiling mount point has limitation that i can't put projector mount on my desired position.

My pictures :)

How big are those screens?

Mine is 280cm wide and 117cm high. The projector is 300cm from the screen. This means much CA. I wanted big image on short distance.

My screen is 110 inches wide, 120 inches on the diaganol. My throw is from about 14 feet back.
http://img42.imageshack.us/img42/2091/screenies010.jpg

http://img5.imageshack.us/img5/3899/dscn26471.jpg

http://img94.imageshack.us/img94/3280/dsc005101.jpg