Film-Tech Forum ARCHIVE: Curved screens vs. Flat screens

This is topic Curved screens vs. Flat screens in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Martin Daian (Member # 1779) on 12-05-2015, 03:17 PM:

Hello everybody, i am concerning about a if is better a curved screen than a flat screen, some dealer lenses explain that the new modern lenses (Isco, Schneiders) not require a vurved screen, but i want to be 100 % sure before to construct my screen, i have 34 feet distance and screen is 17 feet wide by 10 feet high, i want perfect focus on center and corners, other problem is that i have two 35mm projectors with changeovers and one eiki 16mm pedestal projector and one video projector, and i know that never will have a projector on the center of the projection room wall so this will be another situation to have in mind to define if need curved screen or flat sreen,

Any help is apreciated,

Thanks,
Martin

Posted by Mike Blakesley (Member # 26) on 12-05-2015, 04:13 PM:

Given the sizes you indicate, I would say go with a flat screen.

If you want to do a curved screen due to the coolness factor (which is a consideration), then just make sure it's a very slight curve.

Posted by Martin Daian (Member # 1779) on 12-05-2015, 04:47 PM:

Hello Mike, Thank you for write,

Martin

Posted by Steve Guttag (Member # 268) on 12-06-2015, 05:49 PM:

The primary reason t curve a screen at this point is for light uniformity, not focus. On film projection, it could be proven that a curved screen would often improve corner-to-corner focus, particularly on shorter focal lengths but again, light uniformity is the primary driver.

With curved screens you are going to introduce geometric distortions (barrel distortions) that, given your multiple source of film and video, will be different across the various projectors. Since there are not, as of yet, any curved field lenses except for the VERY short Schneider lenses for DLP, some of your light will be wasted in the barrel distortion.

As such, for most installations, I'd recommend a low-gain flat screen (low-gain being 1.0 to 1.3 TOPS with 1.0 being preferred and 1.4 or 1.5 far too high).

Posted by Martin Daian (Member # 1779) on 12-06-2015, 10:21 PM:

Hello Steve, How are you?, Thank you for your recommendations, i will go with flat 1.0 Harkness microperforated screen, also flat screen for me is better to install top and bottom maskings, with curved screen is too much complicated to do the top and bottom maskins, i will use a 1.66:1 aspect ratio screen and will adjust top and bottom maskins for 1.75:1 , 1.85:1 and scope 2.35:1, for Academy format will open the top and bottom maskins for 1.66 and close the side by side maskins a little , also i will install curtains in front, i love silk velvet curtains but is too expemsive and will use polyester false velvet red curtains, also for the maskings will use false black velvet curtains, is too much cheap and will find in our market, the real velvet curtains, the old style velveet curtains was of Scalamandre Italian Velvet Fabrics, arround $ 25 per sq. feet, was high density silk velvet drape with a solid strong cotton base, i remember the smell also,

Thank you again,

Martin

Posted by Terry Monohan (Member # 8285) on 12-13-2015, 03:06 PM:

I don't understand why the large curved screen now in place at the Cinerama Dome Hollywood has black masking bent up on the bottom right and left corners. In the old days this huge curved screen projected a nice full curve from the top to the bottom, there was no masking going up on the bottom corners, at least not as much as they have now. I thought someone had made a new lens for digital projectors on a deep curved screen to avoid this bottom corner problem. I have seen some of these lens for film and DLP that will project on a large curved screen and the titles don't wrap around or bend as they appear flat/straight on a curved screen. The better the curve is great for me. Bring back D-150!!!!!Someone must still have locked up the D-150 screen set up and correct lens.