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Help with selecting 2.35 screen size and other CIH questions

post #1 of 12
2/20/13 at 6:38am
Thread Starter 
Hoping the 2.35 CIH crew can perhaps help me out with selecting a screen size. I'm ultimately looking to go Seymour AV AT-screen. 2.35:1 ratio, but would consider a curved screen if its needed.

The current unfinished dimensions of my theater build are 172" wide by 244" long. From left to right ,I figure to eliminate 10" for framing+drywall leaving 162" of space to be used for screen-width.

My initial plan was to create an AT space of about 30" deep... minus ~5" from the back wall for framing+drywall and thats 208" from back wall to screen wall.

How big of a 2.35 screen can I go along with the use of an A-lens (likely the Prismasonic). My initial thought was 120" wide... but can I get away with 130"? or 140"?

Is the throw distance (or throw ratio) measured from the front of the projector or with the A-lens in place?
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post #2 of 12
2/20/13 at 8:12am
Really how big you can go is going to be determined primarily by the brightness of the projector you are using, plus your seating distance and preferences.

At Panamorph we use screen height to determine throw ratio, rather than width. Using height eliminates the confusion around whether or not you use the 2.35:1, 2.40:1 or 16:9 width. Typically we recommend a throw ratio of at least 2.85X the screen height, which should also work if you end up with the Prismasonic. It is a bit safer to judge from the front of the anamorphic lens, since longer throw distances are almost always better for anamorphic setups.
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post #3 of 12
2/20/13 at 8:45am
Thread Starter 
If I had to buy the projector today, it would be the JVC 4810... but what will likely happen is I will wait for the next generation of JVC projectors until I make the purchase.
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post #4 of 12
2/20/13 at 9:16am
Quote:
Originally Posted by sonichart View Post

If I had to buy the projector today, it would be the JVC 4810... but what will likely happen is I will wait for the next generation of JVC projectors until I make the purchase.

I am running a JVC HD750 with a Panamorph DC1 on an 11 foot wide 2.35:1 screen - it's *just* bright enough with a new bulb, set to standard (low) power. Stewart StudioTek 130, so a 1.3 gain.
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post #5 of 12
2/20/13 at 9:37am
Thread Starter 
Quote:
Originally Posted by John Schuermann View Post

I am running a JVC HD750 with a Panamorph DC1 on an 11 foot wide 2.35:1 screen - it's *just* bright enough with a new bulb, set to standard (low) power. Stewart StudioTek 130, so a 1.3 gain.

I don't have room in the budget for a Stewart screen (wish I did!), but I think the Centersatge XD has a 1.2 or 1.3 gain to it.

My main concern is whether I will experience pincushion effect given my distances that would prompt me to purchase a curved screen. I'm not too concerned about brightness (yet), as I don't like a super-bright image. I have a Panasonic GT50 and I think that the THX Cinema setting for movies is too bright in some scenes... Almost creates a blurry-halo effect to my vision (future wife's vision as well).

Would an 11-foot wide, 2.35:1 image require a curved screen using an A-lens from the distances I mention above?
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post #6 of 12
2/20/13 at 3:45pm
Quote:
Originally Posted by sonichart View Post

I don't have room in the budget for a Stewart screen (wish I did!), but I think the Centersatge XD has a 1.2 or 1.3 gain to it.

My main concern is whether I will experience pincushion effect given my distances that would prompt me to purchase a curved screen. I'm not too concerned about brightness (yet), as I don't like a super-bright image. I have a Panasonic GT50 and I think that the THX Cinema setting for movies is too bright in some scenes... Almost creates a blurry-halo effect to my vision (future wife's vision as well).

Would an 11-foot wide, 2.35:1 image require a curved screen using an A-lens from the distances I mention above?

As long as you are at least 2.85X the screen height, you will probably not find the pincushion objectionable at all. For an 11 foot wide image, your screen height would be 56". 56" x 2.85 = 159.6", or about 13.5 feet. The further back you go the less pincushion there will be. Since your room is about 20 feet deep and you only plan on a 30" deep acoustic space behind the screen, that gives you about 17 feet to play with. I am not very familiar with the Prismasonic lenses, but these figures should apply to it as well. The Panamorph sweet spot is 14.5 - 17.5 feet and I would think that the Prismasonic should work about the same.
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post #7 of 12
2/20/13 at 3:59pm
Quote:
Originally Posted by sonichart View Post

I don't have room in the budget for a Stewart screen (wish I did!), but I think the Centersatge XD has a 1.2 or 1.3 gain to it.

Just so you don't get your expectations too high, XD's gain is well documented at .94 -1.0 ....very good for a weave.

http://www.accucalhd.com/documents/accucal_front_projection_screen_report.pdf
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post #8 of 12
2/20/13 at 6:33pm
Thread Starter 
John,

Thank you very much for the replies. This definitely helps with consideration for screen size as I have little doubt in going the A-lens route. I still have to educate myself on the difference between Panamorph and Prismasonic .... cylindrical v. prism .... etc etc. before making a purchase, so I guess its back to searching through the dungeons of AVS for an answer. It seems like there is very little side by side comparisons of lens or reviews of anything.



Bossman,

Thanks for the headsup with regard to the screen gain of the Centerstage... I'm actually relieved that the real-life numbers are lower than advertised as I don't particularly care for a super bright image. As I stated earlier, I feel like my Panasonic GT50 plasma is too bright (blurry halo effect) when using the default THX Cinema mode. I'm not sure if its my vision, but I don't much care for the effect...
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post #9 of 12
2/22/13 at 2:07pm
Quote:
Originally Posted by sonichart View Post

John,

Thank you very much for the replies. This definitely helps with consideration for screen size as I have little doubt in going the A-lens route. I still have to educate myself on the difference between Panamorph and Prismasonic .... cylindrical v. prism .... etc etc. before making a purchase, so I guess its back to searching through the dungeons of AVS for an answer. It seems like there is very little side by side comparisons of lens or reviews of anything.

I appreciate your comments.

FYI, Panamorph lenses are not straight prismatic, but a cylindrical / prismatic hybrid.
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post #10 of 12
2/28/13 at 6:57am
Yup, AFAIK all the "good" "prism" lenses we talk about here have a cylindrical element(s?) to correct CA and Astigmatism.
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post #11 of 12
2/28/13 at 2:32pm
Soinc, I hope you don't mind if I ask a question in your thread. Hopefully you find it relevant too. smile.gif

I was wondering what do you give up on a cylindrical / Prism hybrid vs an all out cylindrical lens?
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post #12 of 12
3/1/13 at 2:40am
Quote:
Originally Posted by stanger89 View Post

Yup, AFAIK all the "good" "prism" lenses we talk about here have a cylindrical element(s?) to correct CA and Astigmatism.

CA correction is part of the prisms themselves (doublets made from two glass types cemented together), not the cylindrical astigmatism corrector. The cylindrical astigmatism corrector is typically a singlet made from BK7 glass.
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