Posted on March 14, 2008 By Art Feierman
Some projectors have a lot of placement range, while others are severely limited. With few exceptions, 3LCD projectors and LCoS projectors are extremely flexible, with zoom lenses with plenty of zoom, and all of these two groups of projectors have lens shift. By comparison, the DLP projectors consistently have very little zoom range. Some of the DLP projectors have lens shift others do not. Even when they do have lens shift, they don’t have as much as the other types.
Let’s discuss the issues, then get into the individual projector’s abilities.
Lens shift is a requirement if you want to shelf mount a projector in the rear of your room. It allows the projector to maintain a proper, rectangular image on the screen from different heights, and for a projector placed higher than the mid-point on the screen, without lens shift, the projector must be inverted, so, essentially, ceiling mounted.
The other thing you need to shelf mount, is a projector that can be placed far enough back to sit on a rear shelf. Of course your room length and screen size come into play. Let’s say that those projectors without lens shift normally also have lenses with very little zoom range, so their throw distance range is normally kept fairly short, figuring that ceiling mounting is easier, closer to the screen.
Here’s a chart organized by our three Classes. For each projector, it provides placement information in terms of distance and height, for a 100 inch 16:9 screen. Using these numbers, you can determine the ranges for any sized screen just with a simple calculation.
* Planar PD8150 – is interesting in that the lens shift is unequal. It can be placed higher above the screen top, than it can be lower, below the bottom.
** The Optoma HD8600 can be placed up to 4.9 inches above the top of the screen surface, but only down to 14.9 inches above the bottom of the screen.
*** The InFocus SP8602 has the most unusual lens shift. The top number shown is correct, the SP8602 can be placed that far above the top of the screen. What is weird is that the lens can only be placed from that height, down to the top of the screen surface, but not below. So you can not have the InFocus SP8602 mounted, say a foot below the top of the screen. All the other projectors with lens shift would work there.
Note: All numbers above are approximate. Throw distances should be accurate within about one inch. In terms of Maximum shift, and especially the amount of shift (offset) on projectors without adjustable lens shift, we have found that manufacturers often make errors!
We recommend you double check the numbers with the manufacturer’s tech support, for accurate lens shift numbers. (At least two of these manufacturers show conflicting information in their brochures, compared to their manuals, on at least one model.
For your convenience, below, the home theater projectors are organized first by price class, then by amount of placement flexibility. The four categories are:
Greatest Placement Flexibility (excellent zoom range, lens shift)
Good Placement Flexibility (moderately good zoom range, lens shift)
Fair Placement Flexibility (typically limited zoom range, lens shift, there are exceptions)
Poor Placement Flexibility (limited zoom range, no lens shift)
None of the projectors listed as Poor can be shelf mounted. Those rated Fair can be shelf mounted, but have very limited range and may not work out in most rooms.
Keep in mind that if you plan to ceiling mount, there isn’t that much difference between the four groups, unless ceiling height is an issue, in which case Poor Placement Flexibility projectors may still be a problem as they lack any lens shift.
The key benefit of ceiling mounting is that you can place the projector closer to the screen which often means a brighter image.
Key benefits of shelf mounting include usually easier to get power to the projector (installation time and cost), less audible noise, easier access, generally simpler to install and align.
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