Projector sharpness is very good on all these 1080p projectors, but there are still differences. Not one of the projectors covered has an image that appears sufficiently soft or lacking in detail, to be a serious issue. That said, some folks will consider sharpness differences between some of these projectors to be enough to consider it in their final decisions.
A few thoughts before we get started. It seems that these days, the sharpest projectors tend to be the DLP projectors. While there are some very sharp 3LCD projectors, I'd say the best of the 3LCD crowd still doesn't appear quite as sharp as most of the DLP models. As a rule of thumb, the LCoS projectors we've tested (LG, Sony, and JVC), seem a touch softer than the DLP models.
The question is why? The answer, however, is: "not sure". Still, this is a good place to speculate.
Of the three projector technologies, only DLP is a single chip. LCoS and 3LCD both use three panels (red, green, blue) and recombine the light using a dichroic prism.
In many reviews you see mention about pixel alignment with those 3LCD and LCoS projectors. Basically, it's essentially impossible to perfectly align the three panels. With an extremely well aligned projector, you are still probably looking at at least one color panel to be off as much as 1/4 pixel, either horizontally or vertically. This gives you that fine color fringe (typically red on one side, green on the other), on fine lines or a severe change from white to dark. Keep in mind, that you won't normally see that from your typical seating distance, only if you get much closer.
More typically, those projectors might be off a half pixel one way, and perhaps a quarter pixel the other way (talking vertical and horiztonal). We've even seen projectors where one panel is off by more than a pixel, but that seems to be rare, and would normally be considered a defect by the manufacturers.
At this point, I attribute the typically slightly softer look of 3LCD and LCoS projectors (compared to DLP) to pixel alignment. It doesn't even matter why, only the final result, of course, matters.
One more thing: A few projectors are now featuring digital compensation to allow better pixel alignment. Most notably, JVC has offered it in the older RS1 and RS2, and all the newer projectors. The weakness of digitally aligning them is that you can only move a panel's image over in increments of one pixel. That means if you have a panel about 1/3 off, you can't improve on it. But, if a panel is off by 3/4 of a pixel, moving 1 pixel in the right direction, and now you are only off by 1/4 pixel. Better!
My next point relates to sharpness controls. Every projector has them. Most projectors, out of the box, have default settings that tend to be slightly oversharpened. While that can give you a very crisp looking image, it doesn't improve, actually it can decrease true detail sharpness. So, be careful out there. When you adjust your sharpness, don't get carried away. As soon as you start seeing shadows separating dark and bright areas that should be cleanly separated, your sharpness setting is too high. Then there are dynamic sharpening tools typically with names like edge sharpness, dynamic sharpening, etc. They too can give you that sharper look, and, if you prefer that, go for it. Keep in mind though, that from a purist standpoint, you want to avoid technology that provides the illusion, but no substance, for the illusion is usually accompanied by some loss.
The last point I would like to make is film vs. digital. We have been in love with movies for about 100 years, and, with the few exceptions, movies are shot with film. The film used has lots of resolution, but has its own artifacts that it adds to the overall picture. Obviously film grain is one of those things. For this reason, watch a film movie (on Blu-ray) and a similar scene shot and delivered digitally, and you will have a sharper looking image with the all digital scene. For this reason, my take is that sharpness differences are going to be more noticeable when watching Discovery HD, or a live sporting event, than on a movie.
Finally, I do tend to notice the differences, and for two reasons. Both of these reasons lead me to believe that for the vast majority of folks looking for projectors, there really is no issue. First, I have a large screen, and I like to sit close. My eyeballs are only about 11.5 feet (2.92 meters) from my 128" screen. That gives me a much larger picture (and relative pixel size), then, say, a person with a 110" screen sitting 14 or 15 feet back!
The other reason is vision. I've never had the guts to give up glasses for laser surgery, for fear that my vision would not be quite as good as it is with my glasses. I'm still capable of reading the 20/15 line, at least with both eyes open. So, I'm "cursed" with two problems: I like a really large image, and my vision is extremely good. (Where are those "4K" projectors and matching content?)
For this article I am describing projectors with just two terms, average, and sharper still. Below I will simply list the projectors as one or the other, organized by our price categories.
$2100 and under 1080p Home Theater Projectors
Average sharpness: Epson Home Cinema 8100, Panasonic PT-AE4000, Sanyo PLV-Z700, Sharp XV-Z15000, Viewsonic Pro8100
Sharper still: BenQ W1000, Mitsubishi HC3800, Optoma HD20, Samsung SP-A600, Vivitek H1080FD
$2100 - $3500 1080p Home Theater Projectors
Average sharpness: Cinetron HD700, All Epson projectors, LG CF181D, Sanyo PLV-Z3000, Sony VPL-HW15
Sharper still: BenQ W6000, Optoma HD8200, Mitsubishi HC6800, Mitsubishi HC7000
$3500 - $10,000 Home Theater Projectors
Average sharpness: JVC DLA-RS15, JVC DLA-RS25, Sony VPL-VW85, Vivitek H9080FD
Sharper still: InFocus SP8602, JVC DLA-RS35, Optoma HD8600, Planar PD8150