[joecnc2006]

Antone Tried to make one of these before??

http://home.c2i.net/...tvedt/lens.html

[zendance]

Greetings,

Looks like something worthwhile. I priced one of these a couple months ago and it was ridiculously expensive like $800.

Thanks,
Zendance

[Meeper]

What's it do?

[zendance]

Greetings,

The basic idea of an anamorphic lens is to allow you to use the full brightness of your projector while projecting a 16:9 image.

So, what you do is, you put in a 16:9 movie and use software or a setting on your DVD player to stretch the image vertically to fill the whole of the LCD. This is not scaling, BTW. You should still see everything left to right. It's just that the vertical is stretched.

Then the anamorphic lens is used on the front lens of the projector to distort the picture back to 16:9. The result is a totally undistorted picture that ends up being about 20% brighter or so in the resulting 16:9 picture. It also removes the black bars above and below the 16:9 picture (aka letterbox).


This only works for 16:9, not native 4:3 pictures.

Thanks,
Zendance

[Meeper]

Oooh, that sounds a cool thing.

[joecnc2006]

zendance, on Apr 22 2004, 10:05 PM, said:

Greetings,

The basic idea of an anamorphic lens is to allow you to use the full brightness of your projector while projecting a 16:9 image.

So, what you do is, you put in a 16:9 movie and use software or a setting on your DVD player to stretch the image vertically to fill the whole of the LCD. This is not scaling, BTW. You should still see everything left to right. It's just that the vertical is stretched.

Then the anamorphic lens is used on the front lens of the projector to distort the picture back to 16:9. The result is a totally undistorted picture that ends up being about 20% brighter or so in the resulting 16:9 picture. It also removes the black bars above and below the 16:9 picture (aka letterbox).


This only works for 16:9, not native 4:3 pictures.

Thanks,
Zendance

Well said, However I think that is instead of using a 30deg. angle lens what if you use a curve glass or concave glass in the front , then use Brain's earlier results for a zoom lens (thaqt was cheap) that created a barrel effect and then use this lens i'm talking about to correct it?

prob. can make it for about 10 dollors.

[joecnc2006]

Anythoughts??????

[zendance]

No idea, dude. I've never made one of these and never used one, I just know what they do because I read everything.

I am wondering though. If you have a curved lens, wouldn't that cause distortion? I mean, a triplet is a triplet to take care of spherical and chromatic abberations. I would think using a curved lens like that would cause the same thing.

Anyway, the stuff I saw on the link you gave out looked pretty cool. He doesn't exactly give a step-by-step, but I think I could figure it out if I have the inclination after creating my projector. I would also think this wouldn't cost more than $10 because it's just glass, sheet aluminum, water and oil.

Thanks,
Zendance

[BuffTech]

My panel does a good jog of upscaling 720x480 all I need now is an anamorphic lens. I already gave up the idea of using an external up scaler I want to use every pixel on my panel I'm surprised this topic isn't as popular in this forum as @ the DIY Audio forum. without an anamorphic lens cheap or not I guess I'm not building my projector unleas its with a 17 inch LCD.

[Squalish]

Very interesting, I'd heard whispers somewhere about a diy anamorph, but never bothered to check 'em out.

Additional linkage:
http://www.diyaudio....p?threadid=4677
http://ww2.bepo.com/jochen/anamorph/ (Deutschen)

And come to think of it, the idea I had for a keystone adjuster probably has some merit here as well - a semiflexible reflector (Like a 1/8" acrylic mirror the Light Fusion screen people use) might be used in some configuration to widen the beam.

It would need to be placed as you would a 45 degree mirror, but with a horizontal fold in the lightpath rather than the vertical ones that are common around here, and bent so that the curve is visible in the cross section. The bend would be achieved via threaded rods attached to bars framing two opposing edges of the mirror.

This is assuming that the curve that the mirror makes would have the correct properties to avoid distortion of the light as in a house of mirrors. I'm trying to remember the math that governs a material in these circumstances, but I probably never learned it... did it have something to do with e^x?

[SethAce]

Hey joe if you get yours to work I'm very intrested, let us know the results

[JWFokker]

For the lazier members of the forum, does anyone know if maybe, premade prisms are available so that I don't have to cut and glue glass and all sorts of other nonsense? There have to be easier alternatives for the prisms, I'm sure.

[BuffTech]

I had a thought and not even an ingenious thought. Why didn't these guys think of getting these prisms custom cut?. Ok the goal is to build prisms cutting glass and pasting it yourself toghether... ahh... naha... I'm not about to cut glass paste them toghether and fill one with somethig like turpentine oil or water wich becomes moldy and quality degrades over time... no thank you. I found a search directory of possible custom manufacturers. And a really nice page for a custom mamufacturer checkem out!


This is a search directory
thomasnet.com


And there I found this website niiiiice!
www.pgo.com/precisionfab.htm


I figure I'll pay good money for custom cut prisms from
what I've learned in this world nothing comes for free.
If these custom cut prisms cost more than $700 dollars
well that defeats the whole purpose of having them custom
cut :angry: I'm thinking of preparing an e-mail to have these
guys quote me. What do you guys think?

[Agent707]

Do these only work for 16:9? What about 2.35:1 (which is really anamorphoic)?

[Squalish]

From my somewhat vague understanding:
The math he used will stretch an image horizontally by a factor of 33% - turning a 4ft x 3ft (4:3) screen into a 5ft4inch x 3ft (16:9) screen.

Different angular measurements can produce a different curvature - measured in the percent that the screen is stretched horizontally. There is no factor that automatically adjusts for what aspect ratio you input. However: Turning 16:9 into 2.35:1 would require a horizontal stretch factor of 32.2%, almost the same factor by which you turn 4:3 into 16:9. So if you wanted to, you could use the same lense to view all material in either 1.78/2.35, instead of 1.33/1.78.

I doubt that you would want an image stretched from 1.33 to 2.35, it seems like it would appear unnatural to the eye.