8mm Forum: Screen - curved or not curved?

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Posted by Colin Fish (Member # 5679) on November 15, 2017, 01:32 PM:

Hello All, I'm in the process of converting my shed into a film room. I have a 12ft throw and a 10ft wide scope image which at the moment is just on a white wall. I have measured from gate to centre screen, 12ft 3in, and to both out sides of the image,13ft 3in,so quite a difference. I reckon the image will be out of focus on the outer edges so have come to the conclusion that a curved screen may be needed. This is a 35mm setup with a 55mm lens. I don't anticipate such a problem with 16mm or super8mm scope as the image area will be smaller. I am thinking of using 6mm board and bending it, then painting with Matt white emulsion with black velvet as masking. Any thoughts?

Posted by Brian Fretwell (Member # 4302) on November 15, 2017, 02:08 PM:

I don't know about the manufacturing method, though it does sound as if it will work, but I do know that for widescreen demonstrations Tony Shapps had a portable curved screen that broke down into curved sections.
It looked slightly bigger than the one you propose when he took it to my local cine club and it seemed to work well.

Posted by Maurice Leakey (Member # 916) on November 15, 2017, 02:44 PM:

Colin
Why not try and project onto the wall to see if the picture is satisfactory.
If so, you don't really need a curved screen.

Posted by Tom Photiou (Member # 130) on November 15, 2017, 04:11 PM:

Are you projecting that image with the zoom fully open?

I always prefer a slightly smaller image with a better contrast myself, there are many ridiculously low priced screens thanks to the digital market, its amazing how cheap screens are now a days,
i was looking on-line and there are some excellent but very low priced screens thanks to the digital market. i recently replaced my hunter screen with a duronic extra white tri pod screen for less than 50 quid. there are electronic 100 inch 16:9 electronic one for £80 or simple pull down versions for less than £20.
Well worth a look on Amazon. [Wink]

Posted by Paul Adsett (Member # 25) on November 15, 2017, 06:16 PM:

Colin, all anamorphic(and normal spherical) projection lenses are specifically designed to produce uniform focus on a flat screen. Going to a curved screen may in fact degrade focus uniformity across the width of the screen. When 20th Century Fox first introduced CinemaScope in 1953 they had a slight curve on the theater screens, mainly because they were trying to replicate the deep curve of Cinerama, but this was soon found to be unnecessary and was quickly abandoned for a regular flat screen. So go with a flat screen and make sure it is matt white so that you get perfect brightness uniformity from any angle or viewing position.
Similarly, those curved flat panel TV'S are nothing more than a gimmick, they add nothing to the picture quality, and in fact they arguably degrade it.

Posted by Colin Fish (Member # 5679) on November 16, 2017, 03:35 AM:

Thanks for the replies. You chaps are awesome! The suggestion of trying the flat screen first makes sense. I just assumed that the distance difference from inside to outside would affect the focus. Before I run film I need to adjust the take up chain on the projector. I have concentrated on the actual fitting of shelving, seating and painting up to now and the screen build is the next job. I will keep you posted.

Posted by Maurice Leakey (Member # 916) on November 16, 2017, 09:20 AM:

I have been a cinema projectionist all my life and all our screens were completely flat.
We never had problems with the focus of the wider 'scope image.

Posted by Colin Fish (Member # 5679) on November 16, 2017, 12:39 PM:

Thanks for that Maurice, you've done for a living what we all dream we could do! Just out of interest we went to Cineworld today to see 'Murder on the Orient Express'. It cost £28 for 2 tickets, 2 cokes and 1 popcorn. The screen ratio was fixed flat and the movie was adapted scope with no masking,shocker! But the screen was curved.

Posted by Maurice Leakey (Member # 916) on November 17, 2017, 07:40 AM:

Colin
Interesting about the Cineworld curved screen.
I was in professional projection from 1952 until 2001, almost fifty years.
The last Odeon (Weston-super-Mare) where I worked had four screens, all served by Cinemeccanica 35mm with platters.
Digital hadn't reared its head by then! So I can't comment on current practices.

Posted by Maurice Leakey (Member # 916) on November 20, 2017, 03:20 AM:

Colin
Here is an update on your Cineworld experience.
Some of their screens are slightly curved and tilted, they are specially treated for IMAX presentations.

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