Posted on November 12, 2013 By Art Feierman
Ceiling Height Issues: These projectors will likely not work in your home theater if your ceiling height is low, or if ceiling height is average, but screen size is rather large. This is due to a lack of lens shift, combined with a signficant amount of lens offset, that requires them to be mounted well above the top of your screen:
All five lack lens shift, and must be mounted approximately 17 inches above the top of your screen’s surface. That 17 inches is the difference between the top of the screen’s surface, and the center of the lens. Remember, that even mounting as close as flush to the ceiling as possible, the center of the lens is likely going to be at least 7 inches below the ceiling (and that’s tight).
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 17 inches, and the center of the lens, 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 provided are distance from floor to bottom of screen surface (not screen frame).
As you can see from the chart above, if you have one of these projectors, an 8 foot ceiling, and a 110 inch diagonal screen, the bottom of your screen surface is about 18 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.
Since all the other projectors have adjustable lens shift, your only restriction to screen size is if it fits on your wall, with the minimum height off the floor that you find acceptable (without the top of the projector hitting the ceiling).
For example, with that 128 inch screen and a projector with lens shift, the screen height (excluding frame), is about 63 inches. Thus, even with an 8 foot ceiling height, you could have the screen surface bottom as high up as 33 inches (96 inch room height – 63 inches of screen height = 33 inches). Now that would have the top of the screen flush with the ceiling, and doesn’t allow for the screen’s frame, so if you have a four inch frame at top and bottom, the 33 inches becomes 29 inches.
Please remember, we calculate the lower number from the bottom of the screen surface, not from its frame, so the bottom of the frame would be at 25 inches (29 – 4) with a four inch wide frame.
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