My room width is about 15 feet, and I am planning on DIY-ing a 12ft x 5ft AT 2.37:1 screen. I am trying to get a suedo "Sandman" showroom "curved and backlit" effect at a medium budget. Here are the facts:

- HT dimensions: 20 ft long x 15 ft wide x 8ft (7ft soffit height at center of room due to HVAC)
- Front Seating at 12ft, and back row at 17 ft.
- Projector: JVC HD100 (RS2), which has low lumens
- AR lens: HTB-AR 2.37:1 lens with HTB's new SLED

Lets say I do mount the projector at 18 ft (above or slightly behind back row), then I will achieve the perfect 2x throw ratio which should eliminate any pincushion/AR lens effect, so a curved screen is then deemed unecessesary. But what if I want the screen to be CURVED for that nice showroom effect. So my question is, would an unnecessary curved screen affect the screen image if I have a perfect 2x throw ratio with AR lens? and if it does affect it negatively, then how bad is it, and would it even be noticeable? How bad would 16:9 HDTV or Gaming content look?

Challenges:
There is a 7 ft low soffit in the center of the room, thats 8 ft deep, and as wide as the room (15ft) to conceal major HVAC/Wiring. So I will have to drop mount the projector and lens at 1 ft below the 8 ft non-soffited ceiling above the seating area. The only problem, is that I want to ceiling-mount the projector above or right behind the back seat, which puts it at a 17-19 foot distance from the actual AT screen.

Pros and Cons:
By placing the projector and lens at about 18 feet I achieve a perfect 2x throw ration which is optimal for an AR lens (16:9 prestretch width is 107" x 2 = 18 ft).

The bad is that the JVC RS2 has low lumens which can reduce the overall brightness of the projected image at a whopping 18ft throw distance, but at this point, I dont want to have a low hanging projector and lense infront of the seating area or right above the first row, where I could bump it if I raise my arm, plus it will just look funny being in the center of the room, not to mention it could obctruct the view of the back row.

Please let me know what you think, if I can go with a curve, should I go for a slight curve radius? or does it matter at all?

oh man....not a single reply? :( Maybe it should be in the main CIH forum.

Perhaps. I read your post (obviously), I just don't know enough to respond other than this response saying I don't know enough to respond! :)

Perhaps. I read your post (obviously), I just don't know enough to respond other than this response saying I don't know enough to respond! :)

ha ha thanks Papajin, I will give it another day before making a duplicate post in the main cih section

Damnsam77,

The idea of curving the screen is to correct an artifact that is introduced by the anamorphic lens - pincusion. The exact amount will be dependent on the TR and will vary from hardly noticeable on a flat screen to the point that you need to curve the screen just to have stratight horizontal lines. Hopefully, you don't have pincusion that bad.

Curving just for the sake of "cool" is just adding in a problem. The age old saying of "don't fix it if it aint broke" never rang so true here. If you curve the screen beyond what is actually needed to fix the pincusion, you will introduce barreling of the image which is as bad as pincusion, but in the opposite direction...

Mark

Thanks Mark, and that is what I was fearing, sides bowing outwards (barrel-effect), the opposite of pincusion where the top and lower sides bow inward.

With the way my set up is, I will be mounting the projector at 18 feet or so, which is 2x throw ration against the 107" pre-stretched 16:9 image width. So in reality, I should NOT expect to have any pincushion effect which renders curving the screen unnecessary.

So my question is, how small of a curve radius would I be able to get away with where it will be visibly curved but not enough to cause a barrel-effect on a perfectly non-pincusioned image? 40ft radius? 30ft?

I can't quote you the exact curve as it really depends on the projector/lens combo, but if your curve is too extreme, then straight lines begin to bend in the opposite direction to what they were before you curved the screen...

Mark

What if you move the pj up to the minimum throw with the lense? I seem to remember 1.6 being the minimum?? That would move you up almost 4 feet and help your lumens and add pin cushion for your curve. I am curious what would look better the 18' or
14.25' throw??

What if you move the pj up to the minimum throw with the lense? I seem to remember 1.6 being the minimum?? That would move you up almost 4 feet and help your lumens and add pin cushion for your curve. I am curious what would look better the 18' or
14.25' throw??

With any 2 prisms HE lens, the shorter the throw, the more pincusion, but also the worse the focusing will be at the edges...

Mark

My throw ratio is about 1.7. The pincushion effect is not a problem since I have masking. Although the effect shows up on the test pattern, I cannot see any distortion when watching movies.