3LCD, DLP, and LCoS - How These Three Projection Techologies Compare in Home Theater Projectors
6/7/2008 -Art Feierman
Projector Placement - lens shift
DLP projectors - I can't tell you exactly why, but most single chip DLP projectors (even home theater models) lack lens shift. When they do have lens shift - such as the BenQ W5000 and W20000, the range is usually a little more limited than 3LCD and LCoS projectors with lens shift. But, again, most home theater DLP projectors don't have any adjustable lens shift, which means those projectors can be used, placing them on a table top, below the bottom of the screen surface, or ceiling mounted - usually slightly above the top of your screen surface.
3LCD projectors - Have lots of lens shift, and virtually all 3LCD home theater projectors do have adjustable lens shift. Many can be mounted as high as 1/2 screen height, above the screen, all the way down to the same amount below the screen, others have a little less, but all can work anywhere from even with the top of the screen surface, to even with the bottom of the screen surface. The projectors do not have to be inverted, and therefore all those 3LCD projectors can be shelf mounted, as well as ceiling mounted or placed on a table top.
LCoS projectors - The LCoS projectors designed for home theater usage, typically have lens shift similar to that of 3LCD projectors.
Bottom Line: From a placement standpoint most single chip DLP projectors are not shelf mountable, and have an exact offset above, and an exact amount below, where the projector can be placed, and no other options. The other two technologies offer very flexible placement (including shelf mounting), by comparison. Finally, the few DLP projectors with lens shift tend to have less flexibility in placement than the other technologies, but they will have enough for most shelf mounting situations - zoom lenses not withstanding (see next section).
Projector Placement - zoom range
Once again, DLP projectors tend to be the least flexible.
DLP projectors - These home theater projectors tend to have zoom lenses with relatively limited zoom lens range. Most seem to have 1.2:1 - only offering you 20% placement flexibility. For example, for a given size screen, where the closest you can put the projector is 10 feet, then the furthest would be only 20% - 2 feet further back - at 12 feet. A good number of inexpensive (and not so inexpensive) single chip DLP projectors have only 10 or 15% range (1.1:1, or 1.15:1), and Almost none have more than 1.35:1 (that much in itself, is rare).
As a result, even those DLP projectors with lens shift (like some of those BenQ models), more likely than not, cannot be shelf mounted, simply because their zoom's range, may not allow you to place the projector close to your back wall.
I mentioned BenQ's earlier. They offer a 1.2:1 zoom range on most of their home theater projectors, and their 720p PE8720 actually as 1.35:1. Some of those BenQ's and others, will work for your room, especially if you are willing to adjust your screen size to make it work.
3LCD projectors - Most of these actually sport 2:1 zoom lenses - that's right - the furthest back you can place it, would be twice as far back as the closest spot.
For a 100" screen, the numbers crunch something like this. With a typical 3LCD with 2:1 zoom, for that size screen, the projector (measured at the front of the lens) might be as close as 10 feet, and as far back as 20 (2:1).
As I said, most 3LCD home theater projectors offer 2:1, but not all. I can't, however, think of any serious players with less than 1.5:1 (still better than any DLP projectors, in terms of placement), and more likely 1.6:1 or as much as 2.1:1 (Epson Home/Pro Cinema 1080 UB).
LCoS Projectors - This is easy, considering there really are only two brands making LCoS home theater projectors; Sony, and JVC. The Sony models offer a healthy amount of zoom range; 1.8:1, while the JVC models sport 2:1 zooms.
Bottom line: Since both lens zoom and lens shift relate to placement flexibility, consider them together. If some DLP projectors work in your room (them being the most limited), then consider them with the others. But, if these issues make using most DLP projectors impossible for your room, then just cross them off the list, and don't worry about it. You have plenty of other great projectors to choose from.
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Projectors - Physical Size
The only consistent thing to say about physical size, is that there are no small LCoS home theater projectors. Those Sony's and JVC's are as larger or larger than the biggest single chip DLP, or 3LCD models, although a few of each may rival the LCoS projectors.
If you want really small, the smallest are DLP, and the Optoma HD65 - review 5/08 - immediately comes to mind. Generally the DLP projectors without lens shift (most of them) are, overall, the smallest, but many of the 3LCD projectors are the same or not that much larger, than say, most of the Optoma projectors (Optoma has 5 models sharing the same cabinet). Most home theater 3LCD projectors are still pretty small, such as all the Epson's and Sanyo's as well as the best selling Panasonic PT-AX200U (720p), however Panasonic's 1080p projector, the PT-AE2000U, is fairly large, if not as big as the LCoS models.
Bottom line, if you choose an LCoS home theater projector, you are looking at projectors, with footprints of 3 square feet or larger, while most of the others (other than the BenQ DLP's with lens shift) come in around or under 2 square feet. That little HD65 mentioned earlier is well under 1 square foot, making it easy to transport to that summer house, or for a rare business presentation (the still rather small HD71, is actually a full size larger, but its extra brightness makes it better suited for "crossover" use as a business portable projector.