Posted on August 2, 2011 By Art Feierman
Below is a chart which gives several examples. It tells you how far off the floor the bottom of the screen surface (not the frame) would have to be, for four common screen sizes, and four different ceiling heights. Obviously, you can’t have your screen starting just a few inches off the floor, especially if some folks sit behind others. To come up with these numbers we assume a projector without adjustable lens shift, fixed lens offset of 15 inches, and the center of the lens. We assume you can’t mount the projector any higher than where the center of the lens would still be 7 inches below the ceiling (about as high as you can mount it, with a typical ceiling mount). Many mounts may require an even larger distance between ceiling and center of the lens:
Screen size (above) is diagonal screen size, measured in inches.
Measurements (inches) provided are distance from floor to bottom of screen surface (not screen frame).
As you can see from the chart above, if you have a projector like the Mitsubishi HC3800 (has 16.5 inches offset, the most of these projectors. For it, an 8 foot ceiling, and a 110 inch diagonal screen, the bottom of your screen surface is about 20 inches from the floor. That’s certainly about as low as anyone would want. With the same 8 foot ceiling, and a 128″ screen (like mine), you’d have to dig a hole, as the bottom of the screen would be below the floor level!
If your setup is going to be tight, you may want to start by figuring out how close to the ceiling, you can mount the projector. Then add the distance to the center of the lens which will vary depending on how far (vertically) from the top of the projector to the center of the lens.
Distance from ceiling to top (inverted) of the projector + Distance from top of projector to center of lens = Total distance from ceiling to lens center.
Bottom line: This year’s projectors, as a group, are far better than last year’s when it comes to vertical placement flexibility. For openers, not one over $2000 projector in our report lacks adjustable lens shift. Last year we had 3 higher priced projectors without lens shift. In fact, despite the addition of three new entry level $999 projectors without lens shift, this year’s crop of projectors finds that lens shift is finding its way on to more and more DLP projectors (it’s already standard on all LCD and LCoS projectors we reviewed.
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