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Cheap coating opportunity for USA prisms - Page 3

post #61 of 214
Quote:
Originally Posted by Mupi View Post

Sam is able to get 2 coated prisms for 99 euros (some $136 USD)
I presume they are also custom cut. I am sure his mount is easy to
make and wont cost more than 50 bucks.

True, but his prisms are just 70mm high. Mine are 140mm high. Both are BK7 with an optic coating...

Quote:


And now we can get prisms coated in US for affordable cost.
I wonder what is the major difference between the prisms that
we can get in US for $50 a piece to the custom cut prisms or the
prisms used in riduculously priced commercial lens, other than
the fact that they are trophies.

I guess the commercial lenses are expensive just because of monopoly. If there are more manufacturers obviously the price will drop. The prism prices arent going to go up. After all it is a piece of glass and they are used for variousl other
applications including trophies.

With the pro lenses, your paying for a much finer finish. Whilst the trophies look smooth to the eye, under magnification they are not that smooth. True optic polishing takes time and costs money - time is money...


Quote:


Moreover when I have a projector like IN72 which costs $599 or less
I wouldnt want to spend a lot of money for the lens.
These group buy options for a couple of hundred bucks is good enough.

Like I said I tried the $8 ebay prisms and the picture was fine. I am sure
the US prisms (this thread) or sam's prisms would be just fine especially as they are coated.

Hope it works out for you...

Mark
post #62 of 214
Thread Starter 
The prisms were shipped in bulk from L&L last week and arrived at my home on Friday.

I will ship them out to everybody Monday, April 30. You should have them shortly!

Richard
post #63 of 214
Cool! I know what next weekend's project will be...

Thanks again for doing this!
post #64 of 214
Just a quick update: My new prisms have arrived and I am very impressed...

Take a look HERE...

Mark
post #65 of 214
Hi Richard,

Do you have a report yet on how the new coated prisms worked with your projector?

Randy
post #66 of 214
Thread Starter 
I was very busy this week and have not had a chance to set up the prisms in my house. I have a Panny AX-100 but I am watching the NBA playoffs on my new RS-1. Go Warriors!

I finally got the rest of the diy prisms into the mail this afternoon. It took a long time to repack and ship them. A few went out earlier in the week, but most were sent today by USPS priority mail. Look for them by Saturday. Delivery isn't guaranteed for two days, though, so some of you may not see them until Monday. It was the best I could do.

I ended up not trying to match them. Matching is of questionable value anyway. I set four random prisms on my dining room table and found them virtually indistinguishable in depth and angle. There was about 1 mm variation in the long dimension, which should have no impact on the image. I elected to keep the four I had opened and ship the rest untouched. They are all individually wrapped in paper inside of their jewel boxes and I did not wish to handle them. One of mine has a tiny chip on a corner but that shouldn't matter. Nothing matters at the moment--the Warriors are up big with nine minutes to Go!!
post #67 of 214
Just wanted to say I received my prisms today. I did a quick and dirty setup and all I can say is WOW! I'm watching Star Wars Episode 4 in HD right now. The detail is amazing.

These 5x7 coated prisms are much better than my 4x6 prisms I had back in December (I broke them). I have pretty good focus across the screen and minimal CA (my projector is 18' from the screen). Geometry is pretty good as well. You can really only see the 'defects' when viewing test patterns.

When I first arranged my prisms I had reflections all over the place. I did some rearranging and I now have very minimal reflections. The credits from the movie CARS is just about perfect. Here is a quick sketch of how my quick setup looks...



Thanks Richard for getting this together for us!
post #68 of 214
Klemsaba,

Have you built a case yet?

Do you have block out on the ends of the prisms?

Adding these things will only make it even better viewing experience...

And a quick update HERE with BD and my lens at 720P...

Mark
post #69 of 214
I haven't built a case or blocked off the ends yet. I pulled my projector down from the ceiling and placed everything on a table so I could 'play' with the prisms. I did put the prism cases along the sides to help block any stray light shining on the walls.

One strange observation is my prism orientation seems backwards to what I see other people doing.



Building a case is next weekend's project.
post #70 of 214
If your drawing is the same as what you have done with your prisms, then you are correct for HE...

Mark
post #71 of 214
Thread Starter 
Klemsaba,

That is an exciting report, especially since you had a previous set of different prisms. Let's hear from others who now have their coated 5x7 prisms. I'd also love to hear from those who have mixed sets of CF and Massillon prisms. Any detectable differences?

I was down for the count with food poisoning all day today but I am looking forward to setting mine up soon. I will compare the performance of two versus four prisms.

What is the best way to black out the ends of the prisms? I have heard some people use electrical tape but I wonder if it would peel too easily.

Richard
post #72 of 214
Quote:
Originally Posted by rcgustafson View Post

Klemsaba,

That is an exciting report, especially since you had a previous set of different prisms. Let's hear from others who now have their coated 5x7 prisms. I'd also love to hear from those who have mixed sets of CF and Massillon prisms. Any detectable differences?

I was down for the count with food poisoning all day today but I am looking forward to setting mine up soon. I will compare the performance of two versus four prisms.

What is the best way to black out the ends of the prisms? I have heard some people use electrical tape but I wonder if it would peel too easily.

Richard

The idea is to minimize reflections. I took black paint (use the black you buy in bottles at your local hobby store instead of the black you can buy at home depot. The black at the hobby store is much more black than home depot), add a bunch of powdered corn starch to it and paint a few coats on the edge of the prisms. You have to be careful, because once it dries, it will scratch easily off, but this provides a very black, inky non-reflective coating to the ends of the prisms.
post #73 of 214
Thank you Richard I received my prism today all the way up here in Canada. Great packing job, crystals look perfect.

Now my home theatre setup consists of:

1) DIY Prisms
2) uh... better get cracking
post #74 of 214
Quote:
Originally Posted by rcgustafson View Post

Klemsaba,

That is an exciting report, especially since you had a previous set of different prisms. Let's hear from others who now have their coated 5x7 prisms. I'd also love to hear from those who have mixed sets of CF and Massillon prisms. Any detectable differences?

I was down for the count with food poisoning all day today but I am looking forward to setting mine up soon. I will compare the performance of two versus four prisms.

What is the best way to black out the ends of the prisms? I have heard some people use electrical tape but I wonder if it would peel too easily.

Richard

I bought the Massillon Plaque 5''x7'' uncoated prisms. They have almost
like a mirror finish and give reflections all over the place and also on the
image. The image quality wasnt bad. I am not sure how the reflections
can be prevented by changing the orientation.

Anyway...I just returned it.

I would like to know if the Crystal Factory prisms are not from the same
manufacturer. Is CF a glass manufacturer or just a distributor.

why would the coated prisms also give out reflections?

isnt the primary purpose of the coating to avoid the reflections?

Just curious.
post #75 of 214
Mupi,

You've stated uncoated prisms, but did you block off the ends of the prisms as well?

That will greatly reduce stray light, but the coating just make it that much better...

Mark
post #76 of 214
Quote:
Originally Posted by Mupi View Post

I bought the Massillon Plaque 5''x7'' uncoated prisms. They have almost
like a mirror finish and give reflections all over the place and also on the
image. The image quality wasnt bad. I am not sure how the reflections
can be prevented by changing the orientation.

Anyway...I just returned it.

I would like to know if the Crystal Factory prisms are not from the same
manufacturer. Is CF a glass manufacturer or just a distributor.

why would the coated prisms also give out reflections?

isnt the primary purpose of the coating to avoid the reflections?

Just curious.

You want as perfect a surface as possible to get a better image on the screen. The better the prism surface, the more reflections you probably are going to experience, but that is where the the ar coating comes in. I kind of laughed when I read your post, because to eliminate the reflections from the surface, without coating, you have to introduce some kind of abrasion or something to the surface which will seriously influence the quality of the image.

fact is, these prisms (and any prism used in this context) are going to cause reflections. There are three ways to minimize them:
1. Prism orientation. The reflections comes from the way the beams bounce off the surfaces of the prisms. You can reduce the reflections on the screen by getting the right orientation.
2. Black out the edges (see above). Some of the more serious reflections come from light bouncing off the edges, and since this is the only part of the prism you can safely black out, it is recommended to do so.
3. Coat the prisms with antireflective coating. I'm still waiting to hear side-by-side comparisons of the prisms with and without coating.

I would imagine crystal factory prisms are going to give the exact same reflections as the Masillon plaques.
post #77 of 214
Hi Mark,

What is the best orientation for the prisms if you are making a VC lens?

Randy
post #78 of 214
Thread Starter 
Quote:


I would like to know if the Crystal Factory prisms are not from the same
manufacturer. Is CF a glass manufacturer or just a distributor.

The CF prisms are made in China. I don't know who else distributes them besides CF. They weigh about a pound more than the Massillon version and have a larger angle to them. Some claim this is a little better for our application, but I have not compared them.

The coatings are applied to the two broad surfaces. There was no reason to coat the edges, which must be blacked out.

Steve--powdered corn starch?


Richard
post #79 of 214
Quote:
Originally Posted by CAVX View Post

Mupi,

You've stated uncoated prisms, but did you block off the ends of the prisms as well?

That will greatly reduce stray light, but the coating just make it that much better...

Mark

I guess the reflections were coming off the main surfaces. So I
just returned them. of course I lost the S&H.

I will wait for the pro lenses to become affordable :-)
post #80 of 214
Quote:
Originally Posted by RandyFreeman View Post

Hi Mark,

What is the best orientation for the prisms if you are making a VC lens?

Randy

Whilst this works, I don't really promote this use, but because I use the same size prisms for both front and rear element with my lens, I can simply turn it around (now becomes a HC) and then lay it on its side (now becomes VC - but have to remove the stand). I have not had any reason to change the angles from their position as a HE lens, as the image looked geometry correct in VC mode.

Some tilt may be needed though...

Mark
post #81 of 214
Quote:
Originally Posted by Steve Scherrer View Post

I'm still waiting to hear side-by-side comparisons of the prisms with and without coating.


I can not speak for you guys, but I can confidently state that the coating makes a difference in that it does further control stray light reflections (but may not totally eliminate them) and IMHO, helps as the blacks look deeper...

Mark
post #82 of 214
I have spent some more time with the prisms. Mission Impossible 3 was on Sunday in scope! I haven't seen the HD-DVD version, but the movie looked great on Showtime. I was amazed at the image... usually HD movie channels are a macro-blocking mess or are crop happy.

I didn't notice any reflections except during one scene in the movie, but I can't be sure if it was from the prisms or if that was part of the movie. I didn't think about checking without the prisms in place because I was having too much fun watching the movie!

I can say these new prisms have a better uniform focus than my old Mallison 4x6 prisms. I always had a focus issue on one side of the screen (before I broke them). The new prisms are pretty uniform. As expected, there is a slight defocus between prism/no prism setup, but it is very negligible.

Maybe it is just psychological, but I feel like I have a new projector... and I have 1800+ hours on my lamp! Perhaps the simple fact that I'm no longer zooming my image up 33% to fill the screen is why everything seems clearer.

There is a slight color shift though when using the prisms. Perhaps that is from the AR coating? They are not clear with the AR coating. I haven't done any post prism calibrations or checks.

I'm impressed. I just hope I can build a suitable case to hold the prisms.
post #83 of 214
Quote:
Originally Posted by klemsaba View Post

Maybe it is just psychological, but I feel like I have a new projector... and I have 1800+ hours on my lamp! Perhaps the simple fact that I'm no longer zooming my image up 33% to fill the screen is why everything seems clearer.

Too true there. Nothing like full panel rez all the time...

Quote:


There is a slight color shift though when using the prisms. Perhaps that is from the AR coating? They are not clear with the AR coating. I haven't done any post prism calibrations or checks.

I'm impressed. I just hope I can build a suitable case to hold the prisms.

Off axis, mine look slightly tinted...

Mark
post #84 of 214
Received my prisms, everything looked great, except for the CF boxes, which looked like they ripped apart easily during shipping. Will be a while before I get them set up. Thanks Richard!
post #85 of 214
Received my prisms also. Thanks again Richard.
post #86 of 214
Is anyone able to post pictures yet?

Mark
post #87 of 214
Since these prisms have the coatings on them what is the best way to clean them? I would hate to rub off the coatings.
post #88 of 214
Optic glass cleaner and cloth is said to be the best and most cost effective way...

Mark
post #89 of 214
Here are a few shots.

I have a bow across the top (it doesn't seem as extreme as the photo shows) and the left side isn't vertical. I also don't have even stretch across the screen. Focus is pretty uniform across the screen. I just have the prisms sitting on a table with my projector. I'm sure once I build my case and hang it from the ceiling I can correct some of these issues.



Now for some fun shots where you don't notice any of the problems...

....resized straight from the camera


....resized straight from the camera


....resized straight from the camera


....resized and adjusted levels...
post #90 of 214
WOW very good

Mark
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