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Q: I currently have a flat TV on the wall in my living room and would like to mount a 100-inch retractable screen in front of it for watching movies from an ultra short throw projector that I would place on a console at the front of the room. The only other option I have would be to put the projector on a high shelf at the back of the room, but that involves the usual long cable runs and installation concerns and won't be as aesthetically acceptable as keeping everything up front. What do you think?
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A: Most traditional screens have waves in the material. Think of your curtains or a shower curtain. They just aren't flat. Even if you pull them by the corners, they aren't flat.

Screens have a similar issue and the larger the screen the more prone to having waves in the material it is. Retractable screens have had this issue as long as I can remember. I even remember this as an issue when I was in grade school as a kid.

To have any hope of success with a retractable screen and a UST projector, you'll need to make it a tab-tensioned screen, such as the Draper Premiere model shown here. These screens used tensioned cord down the vertical edges to pull the screen tight and effect a flat surface (see detail).


So, your screen, cheap or expensive, if it is non-tensioned (cheap ones aren't) will likely have or develop waves.

All of this matters because of throw distance. Think about what is going on with a short throw or ultra short throw projector. These projectors throw an image at a very sharp projection angle. This creates a requirement for an absolutely flat screen surface. Any waves or bends to the screen cause severe distortion. Especially towards the edges and the top of the screen.

The solution to this problem is adding more distance between the projector and the screen. The further away the projector is from a wavy screen the less impact the waves on the screen will have on the projected image.

So, yes, you can use short or ultra short throw, but you can't use an inexpensive roll-up screen. In fact, you may need a several thousand dollar screen to accommodate a short throw solution.

Any waves in screen material can cause obvious geometric distortion in the image, as shown on this hung screen displaying a grid test pattern. But the sharp angle at which a UST projects can make even slight ripples more obvious with certain content.

Of course, you can always opt for using a wall or a fixed-frame screen to save money. But, if you absolutely have to use a retractable screen for room design reasons and don't have the budget for a good tensioned model, you will want to place the projector as far from the screen as possible. In that case, it may make sense to go with a more affordable roll-up screen and put the savings into paying an installer to mount a more conventional projector at the back of the room where minor waves and ripples in the screen surface won't be an issue. Just make sure that the projector you select has the appropriate lens to handle a high shelf installation if that's what you've got in mind. Many projectors require a projector mounted near the ceiling to be inverted as they would for a ceiling mount.

Paul Vail has been a professional audiovisual engineer since 1999. He works day-to-day for a commercial integrator and runs his own residential installation company, AV Integrated, out of Chantilly, VA, covering the greater Washington D.C. area. He has been the moderator of the ProjectorCentral Big Screen Forums from their inception more than ten years ago and has installed hundreds of projectors over the years, from entry level basement setups to 4K simulation systems using the latest in 3-chip DLP technology. He enjoys helping others learn about how to get the most value for their money, and setting realistic expectations and goals for the setup they are working toward. You can submit your question for Paul and ProjectorCentral Q&A by clicking here.

Comments (2) Post a Comment
Cory Posted May 12, 2019 3:51 PM PST
Speaking from experience UST are problematic with anything but a metal framed, internally braced screen. I even made a DIY out of lumber, nail strips and ALR screen material and it shows pincushion distortion due to the corners not being perfectly flat (and I'm talk mm differences from each other). Good news is most USTs have a feature that helps correct pincushion distortion by quadrants but it will also soften the image if used more than a few clicks.

It was only a $50 lesson but I would buy an Elite, Draper, Dalite fixed metal frame screen if I had it to do over again.
Bob DeYoung Posted May 14, 2019 2:46 PM PST
I have a 120" motorized screen I got from monoprice - love it. But I can't imagine it working with an UST projector. Way too many ripples - I hate to call them that, because they are not noticeable with my standard front projector, but I know they would affect an UST. My 0.02.

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