DIY anamorphic lens

[mookieo2]

does anyone have the plans, angles and where to get these new "trophy(lenses)". I own a ht company and want to try to make one for my own ht. The original post is not working. any help would be greatly appreciated.

[Steve Scherrer]

I did a search online when looking for these wedges originally, and I found two trophy companies that can order them fairly cheaply, and the source company. I could not order from the source, because they don't sell to individuals, only to distributors--but if you have a HT company, you may be able to set up an account for them, and order them very cheaply. The source is:

http://www.glassgraphics.com/. Click on the catalog and scroll down a little bit on the left. YOu had to look hard, but the crystal wedges are there, about five images from the top.

So I went back to the one distributor that I had been in contact with, and they ordered it for me at cost, I believe (because they were blanks, and not etched in any way). The cost for the prisms were $29 for the small and $39 for the medium. The largest would probably be $49 (I forgot to ask, because I ordered a small and a medium).

The distributor I ordered from: http://www.massillonplaque.com/produ...4&productid=85

Another distributor that was very helpful: http://shop1.mailordercentral.com/aa...?number=RR7216 (By the way, this distributor makes these trophies for the Elks and Rotary club, so if you order them, make sure they are true blanks, and don't have the elk or rotary symbol already etched. The woman told me that they order them at their company, and pre-etch the symbols on them and wait for orders for the remainder of the etching.

Mark: I am very glad your prisms have worked out the way they have. What are the chances you could line these up iwth a Prismasonic HE lens, and compare? I only have a panamorph VC lens, and I don't have a WVGA or WXGA projector, just SVGA. But as I said, when I get the lenses, I will be experimenting with going 2.35:1 from 1.33:1. I am excited to get these prisms. Stupid Labor Day holiday. I may get them tomorrow...

[Mark Techer]

Originally posted by mookieo2
does anyone have the plans, angles and where to get these new "trophy(lenses)". I own a ht company and want to try to make one for my own ht. The original post is not working. any help would be greatly appreciated.

PM me, I have a plan

Originally posted by Steve Scherrer
[B

Mark: I am very glad your prisms have worked out the way they have. What are the chances you could line these up iwth a Prismasonic HE lens, and compare? I only have a panamorph VC lens, and I don't have a WVGA or WXGA projector, just SVGA. But as I said, when I get the lenses, I will be experimenting with going 2.35:1 from 1.33:1. I am excited to get these prisms. Stupid Labor Day holiday. I may get them tomorrow... [/B]

I will contact a friend who has both a H600 and a H1200 and a very long throw 720 projector, fed by a HTPC through an out board scaler and will do a more comparitive test...

Mark

[fisher]

Hi Mark,

Those screenshots look great. Well done.

I have been looking for, but unable to find) any real information about how well commercial lens perform, e.g. specifications for CA, distortion, light transmission or focus uniformity.

I will be very interested to see how well these crystal prisms preform compared to the H600 and H1200. I am also keen to see the difference between the two prismasonic lenses.

It will be hard to guage this with movie screenshots. As you will be using a HTPC would it be possible for you to use test patterns like the ones here (if you don't mind Sammy)?

http://www.homecinema-fr.com/forum/....php?t=29803723

Close up shots of the screen corners would be very telling.

Also, could you give us some indication of the prism geometry. How well does the crystal bend the light?

Greg

[Mark Techer]

Originally posted by fisher
Hi Mark,

Those screenshots look great. Well done.

Thanks, I am very impressed myself

I have been looking for, but unable to find) any real information about how well commercial lens perform, e.g. specifications for CA, distortion, light transmission or focus uniformity.

And you won't because CA, Barrel/Pincushion and other optic distortions are bad, and the manufacture is going to be very reluctant to admit their product has a fault...

The interesting part of a prism based lens (from over the last year) is that the focus remains consistant regardless of the spacing. My understanding of how it works is due to the non parallel surfaces, which slow the speed of light. The result is CA...

I will be very interested to see how well these crystal prisms preform compared to the H600 and H1200. I am also keen to see the difference between the two prismasonic lenses.

So am I becuase so far as I can tell, they have the same clarity, so it will come down to the RI for each...

It will be hard to guage this with movie screenshots. As you will be using a HTPC would it be possible for you to use test patterns like the ones here (if you don't mind Sammy)?

http://www.homecinema-fr.com/forum/....php?t=29803723

Close up shots of the screen corners would be very telling.

Also, could you give us some indication of the prism geometry. How well does the crystal bend the light?

Greg

The last time I did a "shoot out" on this system, we used a combination of HD (1080P) source material and computor text (which is the most sensitive), so most likely, we will just repeat the same tests...

The Prismasonic H1200 won last time round , so given its price point, will be interesting to see how these prisms go...

Mark

[sdspga]

I will be experimenting with going 2.35:1 from 1.33:1.

Steve,

Wouldn't you need some kind of custom scaling to do this? I thought normally the preset scaling was for going 16:9 to 2:35 or 4:3 to 16:9. To go all the way from 4:3 to 2.35, wouldn't you need a little extra stretch?

sds

[Mark Techer]

Yes he will need a combination of H squeeze and V stretch...

Mark

[Mark Techer]

For those that want to know just how good these new prisms are -

Tonight after a quick re-cal, I removed the lens. I did not notice any brightness or colour increase - they are that transparent...

Mark

[Steve Scherrer]

Originally posted by sdspga


Steve,

Wouldn't you need some kind of custom scaling to do this? I thought normally the preset scaling was for going 16:9 to 2:35 or 4:3 to 16:9. To go all the way from 4:3 to 2.35, wouldn't you need a little extra stretch?

sds

Yes, as Mark said, I will need vertical stretch. The problem is that there is no anamorphic 2.35:1, only 16:9 anamorphic stretch. The remaining image for 2.35:1 are black bars that are part of the image itself. So I would need a scaler to stretch the image further to eliminate the black bars (this is no different from any projector in this realm of using anamorphic lenses--however, most people have 16:9 projectors where the first step in the stretch, the anamorphic stretch, has already been done thereby filling the entire panel of the projector, and the scaler does the rest.

What I am doing is trying to use the entire panel of a 4:3 projector. In my case, I am using an SVGA projector, which is 800x600 pixels. My thought is that if I can vertically stretch the 2.35:1 image to fill the entire 600 pixel high panel, then I will be preserving much of the information of the image (especially for HD source material). I don't know if I get a benefit, necessarily from doing this with DVD source, except to significantly decrease the pixel size to eliminate the screen door effect. There shouldn't be any more information on the image, so if effect, by stretching it vertically, I am merely zooming the image out.)

But for HD source material, I should be adding information to the image during the vertical stretch--because instead of scaling down 1080i (540p?-but it would be less because of the black bars...) or 720p (same) to 480p, I am scaling to 600p--which is pretty darn close to HD material. That is my understanding, but perhaps I am wrong on this point.

Anyway, to make a long story short, I had looked into some external scalers, and they are very expensive. I played around in the service menu of my projector, and found that my 4:3 projector will do the remaining stretch. Of course, I am limited to the quality of the scaling of my projector (which is probably not very good), and I am sure one the external scalers could do a better job, but I am content to use the projector's scaler for proof of concept.

Crossing my fingers that my prisms come today.

[Mark Techer]

Hi Steve,

Your benefit will be from using all of the vertical pixels of the projector's panel as opposed to 75%.

2.35:1 / 2 is 1.175 which equals 705 (roughly) pixels of the 800 that you will have, so there will be small portions of unused horizontal pixels when this is done.

Given that we are more sensitive to vertical rez than we are to horizontal, it will actually be better than the letterboxing you would have going 16:9.

Of course to do this, you will need a lens capable of at least 2x stretch...

I wonder just how far the prisms will stretch before they introduce problems?

Mark