Mult-Format Masking
Projector screens are usually manufactured to a specific aspect ration. The most common of these aspect ratios is 4:3 (1.33-1) and 16:9 (1.78-1). Films are produced on DVD in either 1.33-1, 1.78-1, 1.85-1 and 2.35-1 which means there is usually some sort of compromise in the size and aspect ration of the projector screen.Below you will see a little about the things I can do and have done. I may add to this list one day.
Some screen manufacturers produce dual format screens. These screens allow a separate mask to be lowered in front of the viewing screen to mask off the top part of the screen. By also limiting how far the viewing screen opens the combination of these two factors allow for a range of screen aspect ratios to be achieved. The mask for these screens has its own roller and motor unit making the cost of them 2 to 3 times that of a standard electric screen.
After reading a post on AV Forums by Ken, who wanted advice on painting his 4:3 screen to create a 16:9 aspect ratio, I responded with a solution that would avoid the need for him to paint the screen. Ken pointed out that the solution I had offered may cause further problems. He was right; I hadn't properly considered everything.
Within a couple of hours though I had come up with an idea that would solve his problem but I wanted to be sure before offering any further bad advice. Some experimenting and a few drawings later I had invented the Multi Format Conversion that you can read about here. Better than a dual format screen since with this invention it is easy to achieve any aspect ration.
I had just purchased a new screen and my old screen was in the garage. Time for a prototype. It took a few hours to get the prototype working but once I'd finished the result was far better than I expected. Although the result was good I knew it could be better so I set about researching better materials to do the job.
My next conversion was to my new screen. It had only been out of the box for 2 weeks and I was about to completely invalidate the guarantee. Anyway, the conversion got off to a bad start. The screen I used for the prototype was made of a heavy material, fibreglass and vinyl I think. The new screen was a much thinner material. I tried bonding the mask to the back of the new screen but the result was poor and caused some distortion of the screen fabric. A few cans of Pledge later and a screen free of glue I started again. This time I fitted a false back to the new screen and attached the mask to this. Distortion again, this time caused by the material of the false back being creased and not rolling up properly. I removed it all and ironed the false back to get it as smooth as possible. I then re-attached it to the back of my screen. The result was much better but there was still some evidence of distortion. I decided to leave the screen down for the night to see if things improved. The next day all the distortion had gone, my screen looked as good as new. I raised the screen and a few hours later lowered it to see if the distortion was back. It was, but very much less than the night before. I decided to leave the false back and mask fixed to the screen and just use it as and when I wanted to see what happened. That night we watched a film. I noticed that as the screen was lowered the distortion was almost gone. Once the lights were off and the film started I couldn't see any evidence of distortion. The next night I checked things more carefully and found the slight ripple/distortion was only visible when the screen was illuminated from the side. Also the distortion dropped out within about 15 minutes.
As it stands now the distortion of the screen fabric has not returned. I think that just raising and lowering the screen has eventually removed the final slight creases from the false back. I now intend to remove the false back and try another material. I may try pond liner or a similar vinyl type material for the false back. I am very happy with the lined velvet for the mask but I will try something else here too. My objective now is to find a method that works perfectly from the moment it is fitted; no creases or distortion.
If you choose to try this on your screen then take it one step at a time. If you will use glue then try a small amount first to see how easy it is to remove. As long as you can get back to your original screen you will be OK. The most you will loose is the cost of any materials you have purchased to try this. The most I spent on any one conversion was £35 for the Owl Othello.
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