Is There a Post on Explaining the Anamorphic Lens and How to Set it up?

[mnfish]

And maybe what to do with the screen for the different sizes that the movies are shot in?

[mnfish]

FYI... have a SI 16:9 92" screen with a black frame. Maybe I should just stick with that as the bars on top and bottom wouldn't be that noticable because of it (the frame) It would just give a smaller picture? I got this screen new 2 years ago and have yet to set it up..still in the box unopened. They didn't make (transfer..most were put out in 16:9) too many moives on DVD let alone BD that were 2.35:1 back then but most are now?? I would like to go with a 110" now? I got this one at such a good deal and certainly can't sell it and get something new at that price.

[Brain Sturgeon]

Originally Posted by mnfish

And maybe what to do with the screen for the different sizes that the movies are shot in?

Well, there's not a lot to it actually. For the most common type of anamorphic lens currently (horizontal expansion lens), you would need:

• A projector that has a v-stretch function (vertically stretches the image 33% to exclude the black bars from the imaging panel), or a projector and an outboard VP (video processor) that can do the v-stretch function, or a projector and a BD player that will do the v-stretch function (the Oppo BDP-83 has this function).
• The anamorphic lens.

When the v-stretch function is engaged, you simply place the anamorphic lens into your projector's light path to reconstitute the correct proportions to the image, and voila, you have a scope image that is the same height as your 16:9 image, but 33% wider. Here are a couple of pics to show this in action (hotlinked from ScottJ0007 @ AVS):







Now, the lens should be placed as close to the projector's lens as possible, and should be orthogonal to the light beam. For a ceiling mounted projector, this usually requires tilting the lens downward to account for the lens shift-- you want the light beam to pass straight through the lens to minimize geometric anomalies. You can use a geometric pattern that is found on most video setup discs (Spear & Munsil, Joe Kane's Video essentials, AVIA, AVCHD, etc) to help "dial in" the lens.

All anamorphic lenses will introduce a bit of pincushion to the image (the center of the image will look a bit shorter than the edges). This is usually reduced by using a longer throw ratio. Throw ratios above 2 will minimize this. The effect will be more prominent with throws 1.5 or less. You can also use light absorbent edging (velvet, etc) with your screen to hide this effect by spilling a bit of the image on the edging.

Now, when you disengage the v-stretch function, you will need to remove the lens from the light path. A manual or motorized lens sled is frequently used for this purpose. The other way of doing it is to leave the lens permanently in the light path and use a horizontal squeeze function with the lens to get back your normal 16:9 image (your projector or VP or player will have to have this function, of course). Prismasonic also makes a lens that you just flip a switch (manually or with a remote) between modes (it shifts the prisms in the lens) so that you can leave the lens in the light path permanently.

As far as your screen: Most people using anamorphic lenses have a scope screen and then find some way to mask off the unused portion when watching non-scope material. Curtains and velvet/black panels are commonly used. There are screens that have this masking system built in, but these are typically quite expensive. Either that, or live with the "white bars" on the sides of 16:9 material.

Originally Posted by mnfish

FYI... have a SI 16:9 92" screen with a black frame. Maybe I should just stick with that as the bars on top and bottom wouldn't be that noticable because of it (the frame) It would just give a smaller picture? I got this screen new 2 years ago and have yet to set it up..still in the box unopened. They didn't make (transfer..most were put out in 16:9) too many moives on DVD let alone BD that were 2.35:1 back then but most are now?? I would like to go with a 110" now? I got this one at such a good deal and certainly can't sell it and get something new at that price.

Well, you can't really use an anamorphic lens with a 16:9 screen. It's either live with the "black bars" for scope material, or get a scope screen and then either set up a lens or use the "zoom" method to exclude the black bars from your screen.

Hope this helps!

[mnfish]

And so if I want to make an anamorphic lens does anyone know what size prisms to get? I see some in 4x6, 5x7 and 6x7? And is it better to use crystal instead of acrylic?

[Big Daddy]

Originally Posted by mnfish

And so if I want to make an anamorphic lens does anyone know what size prisms to get? I see some in 4x6, 5x7 and 6x7? And is it better to use crystal instead of acrylic?

http://www.zuggsoft.com/theater/prism.htm
http://owyheesound.com/anamorphic.php
http://www.caltos.com/Anamorphic.pdf
http://www.enrarot.net/anamorph/anamorph.html
http://www.panamorph.com/Technology.html
http://appft1.uspto.gov/netacgi/nph-...DN/20020063975

Affordable Anamorphic Lens:
http://www.hometheaterbrothers.com/23901.html

[mnfish]

Wow!! Thanx! Lots of useful info!!