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projector to mirror to create distance


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4 replies to this topic

#1 of 5 OFFLINE   rootbeerwasted

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Posted September 20 2012 - 04:57 PM

I want to set up a screen and a projector behind it in a closet. Can i aim the projector at the wall and using a mirror reflect the image onto the screen where the closet door would be to create more distance? Is there a projector that projects mirrored images and has a short throw lens?

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Posted September 20 2012 - 07:53 PM

I have seen this done for a project.  You can also order first-surface mirrors from the screen manufacturers who make rear projection mirror setups. I know Stewart, Da-Lite and Draper do. You may have to go through a dealer. It may very well be cheaper to go to a glass/mirror shop if you can find one near you.

Using digital keystone correction is a poor substitute for correct alignment. It invariably results in loss of resolution and produces moire' in the image. Such a feature may be tolerable for road warriors setting up for Power Point presentations but not for serious viewing of motion images. The biggest challenge is mounting both the projector and the mirror so that both have minute adjust-ability.



#3 of 5 OFFLINE   DavidK442

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Posted October 14 2012 - 04:13 PM

I have set up my theater projector using a mirror to increase throw. A bit tricky because you have to mount the projector outside of the reflected image. You can use a standard 2nd surface bathroom type mirror to set things up before plunking down the cash to buy an optical grade 1st surface. Initially I thought the regular mirror was good enough but soon noticed very slight banding in light areas across the entire screen. All glass mirrors have wave imperfections that are not detectable during regular use but when you bounce a bright light off of them and magnify the image 5X in a dark room the smallest imperfections become obvious.

#4 of 5 OFFLINE   Bobofbone

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Posted October 14 2012 - 07:07 PM

You mentioned putting the projector in a closet. Projectors can create lots of heat. A closet will require enought ventillation to disapate the heat the projector creates, or the projector may overheat. If the projector is recessed in a closet, make sure the air intake and exhaust are not obstructed.

#5 of 5 OFFLINE   DavidK442

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Posted December 10 2012 - 04:55 PM

An old thread but thought I would give a followup for anyone thinking of using a mirror to extend throw. I took the plunge and ordered a 24"X12" first surface mirror from FirstSurfaceMirror.com. There may be one or two other sources on the internet but this site was referenced from other members so I went there. All in, shipping to Canada was close to $300. At first i was elated. It did appear that this expensive mirror eliminated the banding I was seeing on all standard second surface mirror I had tried...that was until one night when I watched "The Hills Have Eyes" on bluray. This movie has lots of slow day time pans of the bleak desert and clear horizon. (Watching for atomic mutants can be tedious business. :)) Sure enough, I saw striations again. Very, very slight, and much closer together, but definately there. They ran for the most part vertically, but seemed to curve slightly to the left near the bottom of the picture. I believe the mirror was good quality and I don't blame the supplier. When you really start looking for mirrors, I mean research grade mirrors, you quickly find ultraflat polished units running hundreds of dollars for a few square inches. Likely this is the level required to eliminate all aberations, but obviously way too expensive. It makes me wonder how rear projection tv's with their dual mirrors can produce an acceptable image, but then again they project less than 1/4 my screen size. I also wonder if the acrylic mirrors typically used, while being less reflective actually have a flatter surface than even the First Surface glass mirror. My understanding is that glass is made by floating molten sillica on molten metal (lead? aluminum?) which leads to a wave structure. Anyway, I would love for someone with experience to call bullshit and explain what is really going on, becuse for me the banding (which I don't see with direct projection) is really annoying.




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