DIY anamorphic lens

[dvarma]

Sorry, in my previous post, there is an extra period at the end of the link. It should be:
www.caltos.com/Anamorphic.pdf

[MikeP]

dvarma: Nice job! Thanks very much for posting the pdf file with all of the pictures. I've been trying to think of how to mount my lens so that it can be retracted and was thinking about drawer slides, but I kept thinking that I'd make it like a drawer with two slides. I never thought to use just one like you did. You saved me a lot of work on that one.

And I like your bracket for adjusting the height and angle of the lens. All in all, a nice adjustable system.

[morkys]

Originally posted by Mark Techer
So morkys, are you wanting a VC to reduce the image size given that your so close? Just becareful with too much zoom...

Mark

Nope. I am not interested in a VC lens at all anymore. I was only looking for one earlier because I wasn't aware of the difference between VC and HE lens. I thought a cheap used Panamorph 752's would work but as a VC lens it will not work. I realize now that my throw ratio pretty much eliminates my using a VC lens. If I did buy a lens, I would use an HE lens. I prefer the HE setup anyhow, since it makes more sense. You setup your projector to shoot your ideal 16:9 screen size with your constant height, and then you only need to stretch the image electronically and then stretch it horizontally with the lens and you are done, and to go back to 16:9 you just reverse the process. No need to touch the zoom. If I can coat my prisms with a proper anti-reflective coating such as Steve may have found, then I will do that and probably coat all 4 prisms.

[Mark Techer]

Dvarma,

I saw a post you did at AVS but didn't reply as I didn't want to look like I was pushing the DIY lens there too hard - there is an Aussie with the tag Darma who recently bought an Aussiemorphic Lens off me. This thread statred back in 2002 was for that exact reason

Great work and very inventive with the slots and bolts...

Mark

[Steve Scherrer]

I got the Vikuiti films in yesterday. Unfortunately, we had our holiday party for work last night, and I didn't get home until late--I was exhausted, so I had to table my review until this evening.

[dvarma]

Thanks, Mark. If you remember it was your PM to my question on AVS forum a few months ago about prism sources that sent me over here to discover this treasure of a thread

It's no coincidence that the case looks almost exactly like (except I haven't yet cut out the corners on top and bottom on the short side of the case) the Aussiemorphic lens.

Also, I can't tell for sure, but taping two AR coated glasses (one each on each prism) on to the prisms on the projector sides seem to have helped a bit. I know it is not like a real AR coating, as there is potentially gap at the interface, and maybe it is a psychological effect, but I do think it helped. I used the source someone posted on this thread a few weeks back. I am waiting for someone to try and see if they can get the prisms AR coated cheaply. I can't take mine out as they are already epoxied to the bolts, but if it does work I might get a new pair.

Thanks to Mark, Mike, Steve and numerous others for the great info on this wonderful thread!

[dvarma]

Here is a cross hatch that shows geometric distortion and CA I am getting with my setup. Not bad.

BTW, the screen I am using is made from the Wilsonart Designer White laminates, and is 110 inches wide (2.35 AR of course!). The Z4 is just about enough in a dark room.

[MikeP]

dvarma, I don't know if it is too late to do this with your enclosure or not, but it looks like the prism closest to the screen needs to be adjusted to the right (as you are looking at the screen). I think that might be the cause of your severe color problem on the right edge of the screen.

Remember that the light beam coming from the first prism is like a rainbow. The first prism splits the beam into colors. This spreads the beam horizontally and makes it wider. (see How Rainbows work)

When this rainbow beam hits the second prism, the colors are re-integrated (because the second prism has the same geometry as the first).

The red colors are bent the least, and the blue colors are bent the most. Using Mark's prism geometry, and looking into the first prism from the projector towards the screen, the beam enters the first prism, and is bent towards the right, with the blue colors bent the most.

If your second prism is too far to the left, then the blue colors are not hitting the second prism on the right-most edge of your picture, resulting is a loss of blue (makes the image redder).

When aligning the prisms, it's important to put a piece of paper against the inner-face of the second prism to see the incoming beam to make sure you are catching all of it.

For this reason, I have the hypotenuse of the second prism facing inward because this is the surface that really needs to be the largest to catch as much refracted blue light as possible.

More physics in action!

[Steve Scherrer]

Originally posted by dvarma

Also, I can't tell for sure, but taping two AR coated glasses (one each on each prism) on to the prisms on the projector sides seem to have helped a bit. I know it is not like a real AR coating, as there is potentially gap at the interface, and maybe it is a psychological effect, but I do think it helped. I used the source someone posted on this thread a few weeks back. I am waiting for someone to try and see if they can get the prisms AR coated cheaply. I can't take mine out as they are already epoxied to the bolts, but if it does work I might get a new pair.

Thanks to Mark, Mike, Steve and numerous others for the great info on this wonderful thread!

Glad to help--this has been really fun for me to figure out. As for your comment above--I am hoping that the apparent reduction in glare and reflections with using AR coated glass is not just psychological, since I am attempting something similar by using the vikuiti films.

[dvarma]

Originally posted by MikeP
dvarma, I don't know if it is too late to do this with your enclosure or not, but it looks like the prism closest to the screen needs to be adjusted to the right (as you are looking at the screen). I think that might be the cause of your severe color problem on the right edge of the screen.

Remember that the light beam coming from the first prism is like a rainbow. The first prism splits the beam into colors. This spreads the beam horizontally and makes it wider. (see How Rainbows work)

When this rainbow beam hits the second prism, the colors are re-integrated (because the second prism has the same geometry as the first).

The red colors are bent the least, and the blue colors are bent the most. Using Mark's prism geometry, and looking into the first prism from the projector towards the screen, the beam enters the first prism, and is bent towards the right, with the blue colors bent the most.

If your second prism is too far to the left, then the blue colors are not hitting the second prism on the right-most edge of your picture, resulting is a loss of blue (makes the image redder).

When aligning the prisms, it's important to put a piece of paper against the inner-face of the second prism to see the incoming beam to make sure you are catching all of it.

For this reason, I have the hypotenuse of the second prism facing inward because this is the surface that really needs to be the largest to catch as much refracted blue light as possible.

More physics in action!

I will try this. Thanks very much!