What happens when you want to view a 16x9 source? My projector is connected to a PS3 so I still want to be able to play games and have it look correct. I assume I would either have to remove the prisms or make them parallel. If I do that will I have to fiddle with my projector to get it to look right?

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

That is a cool way to greet and welcome guests into your home cinema. I am so going to make me a big CAVX one for mine :)

What happens when you want to view a 16x9 source? My projector is connected to a PS3 so I still want to be able to play games and have it look correct. I assume I would either have to remove the prisms or make them parallel. If I do that will I have to fiddle with my projector to get it to look right?

a few choices (for 16:9 native projector) ..

- remove lens and set projector AR to 16:9 mode
- leave lens in place and set lens to pass through mode
- leave lens in place and set projector AR to letterbox 4:3 mode

i think the best picture quality choice is the 1st. and the worst is the 3rd. For me, i prefer the 3rd choice because i found that when i remove lens, I have to refocus the projector a lil bit. My projector is ceiling mounted so it's kinda hard to do that and i don't want use focus/zoom mechanic too often. Except for very visual pleasant 16:9 medias that i will remove lens and set AR to 16:9 :)

Just think about it, i use near max zoom which cause more ca and geometry distortion for CIH and use letter box 4:3 mode which not use full projector panel for 16:9. Kinda sad for that :(

a few choices (for 16:9 native projector) ..

- remove lens and set projector AR to 16:9 mode
- leave lens in place and set lens to pass through mode
- leave lens in place and set projector AR to letterbox mode



With the first option you do you adjust the zoom and focus or just the focus? The image doesn't move on the screen though right?

Pass through would be setting the prisms parallel right? Do you have to do any adjusting when you do this?

Won't setting the projector to letterbox mode will crop the top and bottom of the image?

With the first option you do you adjust the zoom and focus or just the focus? The image doesn't move on the screen though right?
Only focus, no zoom adjust needed.

Pass through would be setting the prisms parallel right? Do you have to do any adjusting when you do this?
That's right, prisms must be parallel as shown in the very first post by oman321. But my diy enclosure has no lens adjust (turning) part. So i can't try this method.

Won't setting the projector to letterbox mode will crop the top and bottom of the image?
Oops, sorry. Actually it should be 4:3 not letter box mode :p. Letter box mode is used with 2.35:1 movies with lens in place.

That is a cool way to greet and welcome guests into your home cinema. I am so going to make me a big CAVX one for mine :)

Thanks CAVX,

It is actually the warm up screen my projector displays or if there is no input or I blank the image for some reason. It is a nice feature that the Epson's offer which allow you to place your own image in those areas. Others use a dvd to display a jpeg if their proj. doesn't offer that feature.

I was able to crop the image from a proof that another forum member sent me for a marquee sign which he graciously offered to make me. I still have to make a frame for it, once done I will be able to light it up from behind and actually place lettering below it. Something like "Enjoy The Show" or whatever movie I will be showing that night.

Original image:
http://img405.imageshack.us/img405/8067/highlandcinemamarquee2v.jpg

What happens when you want to view a 16x9 source? My projector is connected to a PS3 so I still want to be able to play games and have it look correct. I assume I would either have to remove the prisms or make them parallel. If I do that will I have to fiddle with my projector to get it to look right?

A lot of folks will call this blaspheme but, I often leave the image set to scope and simply remove the vertical stretch. The image fills the entire screen this way. My son and his friends play their games on our PS3 and have never complained about the image seeming overly distorted. As a family we play rock band, my son and daughter play little big planet, and my son plays some 1st person shooters and other stuff as well. Never a problem.

My scaler does offer a squeeze mode which will add bars to the left and right and this allows us to properly display 16:9 if we desire to, but that desire has come up once in over a year. Maybe if I end up doing masking some time in the future, but it's not a priority.

BTW, My lens stays in place all the time and I have my remote programmed to go from 2:35 to 16:9. Unfortunately with my scaler there is no direct input to switch AR's so it takes a couple of steps to get there but it is a sequence that the remote takes care of with 1 button press.

blasphemy!

:D Don't knock it till you tried it!! You just may like it. Rock Band in scope truly rocks!!

Here are a few pics I took a while back to do some comparisons. Just a side note that when I did this testing and I applied 4:3 mode on my scaler it made me realize that the image was being cropped/overscanned when set to 16:9. I found a setting in my projector which actually reduced the amount of overscan that it was actually implementing. I gained about 2 inches top and bottom and about 4-5 inches from left and right which was simply being cropped off before. This further reduces the stretch which is being seen in the pics below.

http://img36.imageshack.us/img36/394/dscn27751.jpg
http://img97.imageshack.us/img97/9969/dscn27741.jpg

http://img267.imageshack.us/img267/4469/dscn27801.jpg
http://img255.imageshack.us/img255/6977/dscn27791.jpg

http://img5.imageshack.us/img5/945/dscn27841.jpg
http://img255.imageshack.us/img255/933/dscn27831.jpg

These shots were with an old 4 mp point and shoot camera so not the best quality but it gives you an idea of what were seeing. The only time anyone is the wiser is if your going back and forth between the 2 apect ratios.

use letter box 4:3 mode which not use full projector panel for 16:9. Kinda sad for that :(

Don't be too sad. Your pixel density remains the same as your scope image as well as your calibration settings. Also, if you have a curved screen, once set up to correct for pincushion, means that will never change either.

Thanks every one for your input. I do plan on trying it out in scope mode. I just want to be sure i have options if I don't like it.

I have another question. I realized that if I make my screen the size I was thinking I am going to have to apply some keystoning to get it to be positioned right. Will this cause me any issues? If so will a projector with lens shift work?

Here are few leftover pictures from my "diy anamorphic lens" article.

*BUMP* *TILT*
(I m refreshing this to bring up a recurring topic that some may do to tweak their setups )

On the zuggsoft website article on the anamorphic lens, there's no 2 ways about it -- there's trade offs with the edges of the image and that goes for the (runco) anamorphic as well. However, it's a good trade off vs zooming your projector to fill the screen.

With respect to buying the "french" prisms the alternative like it was mentioned in the article is to buy the crystals which they make the award plaques. Granted, they're a bit bigger, but, they're made in the US and if we can do a group buy (!!!!!!!) we can get them for around 50 -60 $ a pair from another (wholesale) US source. The lenses while bigger have a bit more to play with. I think this would be good opportunity for those who are tweaking their setups as well as a GREAT DIY project that adds alot to the theater experience.



Frank

PS: I would imagine there won't be issues with chips and scratches that would make anyone including myself get upset. Likely they'd not even blink in sending out replacements. Guys, it pays to get American stuff when you can.

*BUMP* *TILT*
(I m refreshing this to bring up a recurring topic that some may do to tweak their setups )

On the zuggsoft website article on the anamorphic lens, there's no 2 ways about it -- there's trade offs with the edges of the image and that goes for the (runco) anamorphic as well. However, it's a good trade off vs zooming your projector to fill the screen.

Sorry, whilst these prisms do produce optical stretch of 1.33x, these prisms are not even close to the PQ from the anamorphic lens used on the Runco setup. To make such a statement is wrong and means that you have clearly not seen one.

With respect to buying the "french" prisms the alternative like it was mentioned in the article is to buy the crystals which they make the award plaques. Granted, they're a bit bigger, but, they're made in the US and if we can do a group buy (!!!!!!!) we can get them for around 50 -60 $ a pair from another (wholesale) US source. The lenses while bigger have a bit more to play with. I think this would be good opportunity for those who are tweaking their setups as well as a GREAT DIY project that adds alot to the theater experience.

Both the the "trophies" and the "French Prisms" are made in China, not the US and why they are so affordable. The "French" prisms are made from BK7 and do have an optical finish with an AR coating, however they are small. The "Trophies" on the other hand have a surface finish which is far from perfect, as they were never intended to be used as optical elements. Also, because these prisms are made from just one material, there is no CA correction and why they exhibit the colour fringing you see.

HERE (http://www.avsforum.com/avs-vb/showthread.php?p=18105850#post18105850) is a link supporting the difference between two "trophies" and a proper cylindrical anamorphic lens.

Sorry, whilst these prisms do produce optical stretch of 1.33x, these prisms are not even close to the PQ from the anamorphic lens used on the Runco setup. To make such a statement is wrong and means that you have clearly not seen one.



Both the the "trophies" and the "French Prisms" are made in China, not the US and why they are so affordable. The "French" prisms are made from BK7 and do have an optical finish with an AR coating, however they are small. The "Trophies" on the other hand have a surface finish which is far from perfect, as they were never intended to be used as optical elements. Also, because these prisms are made from just one material, there is no CA correction and why they exhibit the colour fringing you see.
As I said, there are trade offs. I ve seen the runco, and I 've seen the prisms, and for me that's not a $2500 difference between them. Yep, there's CA but not $2500. worth. It's like making a screen of canvas, painting it with silverscreen or MMudd. It's good but not as good as A Da-Lite GreyHawk. Same with the prisms. It will work, it's a good DIY exercise as the zuggsoft article suggests. It's a simple and decent project for someone who wants to experience anomoriphic without their wallet being anomorphic!

Frank

I ve seen the runco, and I 've seen the prisms, and for me that's not a $2500 difference between them. Yep, there's CA but not $2500. worth.

Note sure what lens you saw as the the Runco lens is way more than $2500 (AFAIK, ISCO III's are listed at $9K USD) and when I saw it for the first time running BD in front of a 3 chip 1080 DLP in 2008 (at the time I was still using my MK2, which was basically a "trophy lens") , I just said to myself "time for that upgrade". It truly was the 'water to wine" difference to me and the images in the link (http://www.avsforum.com/avs-vb/showthread.php?p=18105850#post18105850) reflect too.

Note sure what lens you saw as the the Runco lens is way more than $2500 (AFAIK, ISCO III's are listed at $9K USD) and when I saw it for the first time running BD in front of a 3 chip 1080 DLP in 2008 (at the time I was still using my MK2, which was basically a "trophy lens") , I just said to myself "time for that upgrade". It truly was the 'water to wine" difference to me and the images in the link (http://www.avsforum.com/avs-vb/showthread.php?p=18105850#post18105850) reflect too.
Panamorphic lenses are around $2500 and so are the prismasonic like the ones on CAVX's blogspot. $9000 for the runco, you say? Even better -- I'd say definately NOT $9000 ( nine grand ) worth of difference! After all, it's "just a movie" and if losing track of reality for a bit is the whole purpose -- which is to suspend disbelief that you're watching a film -- unless you have absolute perfection, you're not going to enjoy the film or any film because that perfection just doesn't exist. So while it's cool to push the tech envelope, it's pennywise to chase returns and specifications at the top of this VERY steep curve.

It's really not that hard to forget that the trophy plaque anamorphic lens has a slight color abberation on the edges. I didn't blow tens of thousands on a runco or christie, so DIY Anamorphic or not, my cheap little projector does a pretty decent job of getting me into the film which for some just wouldn't be possible. What does get me anal though are distractions ( and micro-analysiing the technical aspects of a venue is one I leave home ) like spots or wrinkles on the screen, mis-matched aspects, sound and other glaring types of major fubars.

It's like having a Lamborghini with no real place to drive it, or in my case seeing where I can drive my little Audi.

Panamorphic lenses are around $2500 and so are the prismasonic like the ones on CAVX's blogspot. $9000 for the runco, you say?

Panamorph make a prisms based VC lens for about $2K. Their prisms based HE lens is a fair bit more due to the added correction elements needed to make the image clean - IE CA and astigmatism correction that VC design does not have.

Prismasonic also make prism based HE lenses (with a pass through). They too have CA and astigmatism correction.

The lenses used by Runco are true cylindrical lenses and cost significantly more, however are the only lenses that allow perfect focus from corner to corner and why I also use cylindrical lenses in my MK4 lens.

because that perfection just doesn't exist

It does, however it comes at a cost.

it's pennywise to chase returns and specifications at the top of this VERY steep curve.

Normally, the returns are minimal as you go up in quality in HT gear, however with anamorphic lenses, it seem the more you spend the better it gets and buy a huge difference. The "law of dimishing returns" does not apply here.

Look, I'm not intentionally bashing the DIY lens as I started there myself. In fact I was the guy that posted the very first screen caps (THE ANIMATRIX) when the trophies were discovered in '06. I am just keeping it real though.

We'll I can certainly appreciate both sides, and if I were able to I would love to buy a professional lens, ISCO, Schneider, CAVX or otherwise. Truth of the matter is that it's not gonna happen any time soon.

Having said that I am thrilled that I am able to get into the game in a sensible and affordable way for me. IMO the Surplus Shed prisms outperform the trophy prisms for around the same cost and I have never had any major issue with normal movie viewing. Until I hit the lotto, I will be enjoying my DIY lens.

IMO the Surplus Shed prisms outperform the trophy prisms for around the same cost and I have never had any major issue with normal movie viewing. Until I hit the lotto, I will be enjoying my DIY lens.

And that is due to the surface quality of the glass. You could probably request the S/D figure where you'll never get that from the trophy manufacture. And just because the surface looks smooth doesn't make it so.

Oman's right. Unless you've money burning a hole in your pocket or access to professionally produced anamorphics fairly cheaply, dropping a few grand is pure nuts in this economy. That 2 or 3 grand is good for a few american made power recliners.... or a about 100 or so blu ray titles at retail cost....

CAVX said perfection comes at a cost. We haven't reached that yet - there's always room for improvement. Like the new 2k pixel vs 1080p Sony projectors that actually need fouroda pre-processing to upscale a blu ray image ( and they're just awesome! ) But I bet CAVX will start singing the same tune I'm singing now -- not a dimes worth of difference and certainly not scores of thousands of dollars more than a RUNCO or christie light cannon! Trade-offs? Yes. But then again, I m not pimping projectors or lenses yet, so let's be creative when something ridiculously expensive can be had with a "neat trick" and a little ingenuity .

Oman's right. Unless you've money burning a hole in your pocket or access to professionally produced anamorphics fairly cheaply, dropping a few grand is pure nuts in this economy. That 2 or 3 grand is good for a few american made power recliners.... or a about 100 or so blu ray titles at retail cost....

A good lens is up to three times that, so up to 300 BD at retail.

CAVX said perfection comes at a cost. We haven't reached that yet - there's always room for improvement. Like the new 2k pixel vs 1080p Sony projectors that actually need fouroda pre-processing to upscale a blu ray image ( and they're just awesome! ) But I bet CAVX will start singing the same tune I'm singing now -- not a dimes worth of difference and certainly not scores of thousands of dollars more than a RUNCO or christie light cannon! Trade-offs? Yes. But then again, I m not pimping projectors or lenses yet, so let's be creative when something ridiculously expensive can be had with a "neat trick" and a little ingenuity .

Not sure where your going with this. I was simply stating facts having been there, done that. CA correction bugged the hell out of me so correcting that was a priority, not a maybe. Then I got to experience sharper focus and again I wanted better than I had. I'm not sure how many films you watch. I watch at least one a day and have watched 6 in a day. Why? I am in this industry and watching films is part of the job description.

Hopefully one day CIH will become more mainstream (:rolleyes:I know I'm dreaming) whether that is in the form of projector, lens os some other option, and we can all benifit from a pro made product at a reasonable cost.

Yes it's nice that I can get away with a DIY product, and get the enjoyment of having the cinemascope effect. Can it be better with a pro product,of course. Will my friends and family notice the difference for the difference in cost, probably not unless their enthusiasts like us.

When I 1st started looking into CIH, zooming wasn't really a viable option, folks had just recently started to try and make their own lens' and soon after trophy prisms came about.

I kind of got lucky with the so called "french prism" unauthorized power buy and thought I had lost my money because they took so long to get produced and shipped, but the prisms did show up. I went for these vs. the trophy prisms which were also being pushed as a group buy to be sent for AR coating, at about the same time because they were already AR coated and made of BK7 glass.

Thru a variety of sources I found those features to be good things, including the information Mark has shared here and on other sites. I have always appreciated CAVX's candor about what his product can offer, from the 1st rendition to his latest. He has always been willing to help folks out whether your a DIY'er or using any pro product. Being in the biz makes it justifiable to have the best product you can get and/or make (besides it's probably all a write off).

Hmmmm....I've wanted to get into the biz, in fact I do some stuff as side jobs for folks. If I can get enough business I can write off a pro lens too. :D

I know I'm dreaming again:rolleyes: I got a kid going into college can't afford a carreer change now.

Just been notified that my back order french prisms are in stock - order placed....

Just been notified that my back order french prisms are in stock - order placed....

That's great dbbarron, please post some pics of what you come up with for an enclousure. Some screen shots is always nice too.

Just 'installed' the prisms using the positioning diagram early in this thread. Mounted on a shelf just in front of the DLA-HS15 projector.

A few comments:
1)Definitely no longer in perfect focus.
2)definitely some pincushion distortion - about an inch at the 16:9 extents of the screen; square at 2.35:1 extents (I think).
3)at least a few pixels of horizontal CA at 2.35:1 extents.
4)Despite all this, from the viewing distance, looks great with 2.35:1 content. Even with 16:9 content, the focus, CA and geometric distorsion issues are really not noticeable from the viewing distance.

Can't easily A/B compare, so I just can't say what looks better or worse, etc. Just going to live with the prisms on the temporary shelf for awhile.

All these problems seem typical given this thread. Any comments appreciated.

db

Take a look on the Universal Astigmatism Correction Element (UACE) of Anamorphic Research (http://anamorphicresearch.blogspot.com/2009/11/lens-availability-update.html). It really improves the corner-to-corner focus of a 2 prism-based lens and makes the picture much sharper.

Take a look on the Universal Astigmatism Correction Element (UACE) of Anamorphic Research (http://anamorphicresearch.blogspot.com/2009/11/lens-availability-update.html). It really improves the corner-to-corner focus of a 2 prism-based lens and makes the picture much sharper.

I`ve been thinkin about getting that lens to my DIY lens.
But slight astigmatism doesn`t bother me as much as CA i get with my lens.
So i`ve decided to save that $315 to my future 4 or 5 element lens upgrade. They are just so darn expensive:mad:.

BTW, does anyone have any succesful 4-prisms DIY lens experiences to share?

Just 'installed' the prisms using the positioning diagram early in this thread. Mounted on a shelf just in front of the DLA-HS15 projector.

A few comments:
1)Definitely no longer in perfect focus.
2)definitely some pincushion distortion - about an inch at the 16:9 extents of the screen; square at 2.35:1 extents (I think).
3)at least a few pixels of horizontal CA at 2.35:1 extents.
4)Despite all this, from the viewing distance, looks great with 2.35:1 content. Even with 16:9 content, the focus, CA and geometric distorsion issues are really not noticeable from the viewing distance.

Can't easily A/B compare, so I just can't say what looks better or worse, etc. Just going to live with the prisms on the temporary shelf for awhile.

All these problems seem typical given this thread. Any comments appreciated.

db

Silly question DB, but did you try to refocus a bit?

Donhou,

Cavx once played around with a 4 prisms prototype while he was developing his MK 2. But as i remember, he said that there were too many problems with non-cemented prisms.

To get CA correction to work with prisms, each prism needs to have a minimum of two different refractive index materials cemented together with their apexes opposing so that the final piece of glass is still a prism.

Getting the correct materials, with a appropriate surface quality and bonding without bubbles is why no DIY solution was ever realized.

I am currently using a 4 prism diy lens and hope to add the home theater brothers Universal Astigmatism Correction Element within the next couple months to see how much the focus improves, so far the ca with my diy 4 prism lens looks reduced over the 2 prism, but still have to do some more testing to make sure that it's not my eyes fooling me. I'll have some pictures up soon...

Are both apexes of each prism pair facing the same direction?

Cavx, I'm not quite sure that I understand your question, could you give me further explaination or a quick sketch of what you mean by "apexes facing the same direction"? My current setup of the prism pairs is like so:see attachment... Might have to hold off on the pictures for a while because they are coming out terrible, have to read the camera manual once again.

Thanks to everyone who has contributed to the diy anamorphic lens research...:)

Cavx, I'm not quite sure that I understand your question, could you give me further explaination or a quick sketch of what you mean by "apexes facing the same direction"? My current setup of the prism pairs is like so:see attachment... Might have to hold off on the pictures for a while because they are coming out terrible, have to read the camera manual once again.

Thanks to everyone who has contributed to the diy anamorphic lens research...:)

Based on the attached image, CA correction can not work. The diagram shows what would be 4prisms (2 prism pairs) of the same material and same angle and same orientation.

CA correction would require one prism of each pair to be:
1. reversed
2. made of a different material
3. have a different angle to the other prism.

If you were to reverse one prism of each pair you will find that the prisms now form a rectangle.

Is this making sense?

Ah, yes, that's what I was confused about, the prisms in each prism pair have to be facing in opposite directions, one apex up, one apex down, so this is not going to work with these trophy prisms, because the angles would not allow to keep a prism shape, instead they would form a rectangle box, not allowing for proper stretch. Did some more testing, and it seems that the CA is not actually reduced, :(, but will continue to test and see if there are any improvements with the 4 prism lens... Thanks Cavx

Do you remember seeing different angled prisms (trophies) on the DIY Audio site? There was a Perspex prism at some 30degrees and I think if you combined it with a thin optic glass trophy of say 8 degrees (oppose the apexes), you might have some luck. The end prism would be HUGE (not to mention heavy), however you'd have two different materials and still retain a basic prism shape. A pair of these could then be used to make an anamorphic lens. I'm not saying it would even work, but might be worth looking into given that what was done at DIY by myself and others was also not supposed to work.

Oman321, thanks for your inputs here.

I tried the surplus shed prisms with benq w6000 and the results are very good to my eyes.
There is some CA on the left side, but it is apparent only with grid pattern, I don't see any issues with movies.

I will probably stick with these for now.

Thanks!

There is some CA on the left side
If these prisms are aligned properly, you should be getting equal amounts of CA on each side, not just the left.

If these prisms are aligned properly, you should be getting equal amounts of CA on each side, not just the left.

Will try again when my screen is ready. Now I had projected off a wall for testing.

The final throw will be 14ft vs 10ft now, so I guess CA will get more pronounced?

Will try again when my screen is ready. Now I had projected off a wall for testing.

The final throw will be 14ft vs 10ft now, so I guess CA will get more pronounced?

If your increasing your TR, then CA should be [slightly] less. It takes achromatic doublets to correct CA. To align these properly, you are going to need a screen with an AR of 2.37:1. It is also good if you have side masking back to 1.78:1 to ensue that your projector is perfectly centered before you add the prisms.

If you don't have a Scope screen yet [or side masking], another way to do this would be to:
1. set up your projector at the same throw you will use in the final system
2. project the native 16:9 image on your wall and use masking tape to mark out a 16:9 screen
3. run the projector in 4 x 3 mode and align the prisms to that.

Doing so will set them to roughly 1.33x so that won't change [for a given throw] when you make your Scope screen and you will be one step closer to Scope.

The thing to remember is, even though one prism is larger, both have the same 20 degree angle. When your alignment is correct, CA will be even on both sides. You'll also have astigmatism, and you can't fix that without additional cost, but at least you will know why it is there.

Oman321, thanks for your inputs here.

I tried the surplus shed prisms with benq w6000 and the results are very good to my eyes.
There is some CA on the left side, but it is apparent only with grid pattern, I don't see any issues with movies.

I will probably stick with these for now.

Thanks!

Glad to be of service. Just my way of giving back to this awesome community. I still enjoy the great bargain these prisms are and the performance vs. cost ratio they deliver.

Post some pics once your set up, its nice to see others setups.

If these prisms are aligned properly, you should be getting equal amounts of CA on each side, not just the left.


Hi CAVX & dukeav,

I recently bought these prisms too, and I also get some CA on the left hand side only. I have spent time trying to mitigate this but it seems no matter how I place the projector (horizontal plane) and/or adjust the lens shift, the CA stays on the left side and I don't see any on the right, just slightly fuzzy white vertical bars.
It is not a big deal as the CA isn't intrusive during video, but if I could minimise it further by even-ing it out then that should be an improvement.

I will spend some more time checking the alignment, are there any good methods for this? i.e.: establishing the centre and right angle.
Also, I wonder if height positioning adds to this, my projector sits about a foot higher than the top of the screen, I'm aware that this will give me a trapezoid shape picture, but I wonder if this will increase CA or is CA just a horizontal placement artefact?

Relevant specs:
PJ (JVC HD350)
Throw 200" (16.6ft)
2.37:1 Screen width is 106" (8.83ft). 16x9 is 79"
Seating distance 126" (10.5ft)

Cheers all

I wonder if this will increase CA or is CA just a horizontal placement artefact?
CA will be most noticeable on high contrast vertical lines in the image.

Glad to be of service. Just my way of giving back to this awesome community. I still enjoy the great bargain these prisms are and the performance vs. cost ratio they deliver.

Post some pics once your set up, its nice to see others setups.

Will do. For now I have used (no laughing please:)), the cardboard box the prisms came to make the enclosure. Let me see if I can make it more professional...

Hi CAVX & dukeav,

I recently bought these prisms too, and I also get some CA on the left hand side only. I have spent time trying to mitigate this but it seems no matter how I place the projector (horizontal plane) and/or adjust the lens shift, the CA stays on the left side and I don't see any on the right, just slightly fuzzy white vertical bars.
...


Mark and oman321 are the experts, from Mark's comment I am guessing the having the projector not exactly square with screen may be causing to have CA only on one side. So try squaring the projector without prisms first...

My stuff is back in the box for week before I install everything, so I can't test. Mark/Oman321?

Will do. For now I have used (no laughing please:)), the cardboard box the prisms came to make the enclosure. Let me see if I can make it more professional...

:D That's awesome...

I used to think that CA was primarily only in the left because it is most evident in the far left edge/side of the image. There is a CA effect that is viewable from top to bottom on the left edge of the image. Not long ago someone saying it was present on the right and that it is easiest to see with a grid pattern. So I threw the grid pattern from my scaler up and got close to the screen (within a foot) to see that in fact it was there on the right side. Not at the edge as much but within the first 2 feet of the right side.

The good news is that in normal viewing it has never been an issue. The left side is just zoomed a tad onto the border to get rid of that leading edge.

Hi all, thanks for the replies.
I must apologise, I just re-read my post and realised I forgot to mention that the CA I see is when looking at a test pattern, specifically the HCFR Anamorph one. The CA isn't usually that noticeable during normal film viewing, except perhaps for CGI stuff. I believe focus/astigmatism is a bigger issue for me.

I was just adding to what a couple of others here have said about the french prisms as it seems a few people get the CA on the left hand side only, perhaps the un-equal prisms factor in to this...
Taking Mark's advice I have moved the projector about as central as I can determine using rudimentary measures, (it would be useful if I had some sort of giant set square :-) but I still get the CA on the left side only, I will try adjusting the actual prisms again, but I don't hold much hope as that was where I started...

Back to focus, are there any astigmatism correction devices out there suitable for a DIY lens, including those based on french prisms?

Thank again guys

Just take a look on the UACE of Anamorphic Research (http://www.anamorphicresearch.com/store.html). That's what you need.

Just take a look on the UACE of Anamorphic Research (http://www.anamorphicresearch.com/store.html). That's what you need.

Thanks Widlarizer, I'll check it out, I had come across it before and suspected it may only be suitable for their lens? I guess that if their solution is based on 2 prisms then theoretically it shouldn't make any difference which prisms are used...