3LCD, DLP, and LCoS - How These Three Projection Techologies Compare in Home Theater Projectors
6/7/2008 -Art Feierman
Projector Black Levels and Contrast
For years "the Holy Grail" of home theater has been the quest for better black levels. Fixed pixel displays (which include DLP, LCoS and 3LCD) cannot produce a pure black. Ultimately black comes out dark gray, or very dark gray, or extremely dark grays. Only those old CRT projectors could produce pure black (the absence of any light, and those CRTs have plenty of their own issues.
So, for the last 7 to 8 years - the total history of (non-CRT) home theater projectors on the market, has seen a steady improvement in black levels. Until two years ago, however, DLP technology was giving 3LCD and LCoS a serious whooping in this area.
Before I get into it further, a word about contrast. Until a few years ago, there was pretty much a direct correlation between contrast ratio, and how good (how black) the blacks came out. Then came the dynamic irises and dimming lamps, and now the contrast specs are almost meaningless. Today we have projectors claiming 15000:1 contrast that on many scenes can't outperform projectors from two years ago, claiming only 3500:1.
So, what gives?
First let's consider native contrast: DLP projectors (even business ones), have been using DLP chips called Darkchip2, or Darkchip three, as far back as five or so years (let's not quibble). The less expensive Darkchip2 (DC2) has been around for all that time and the Darkchip3 about 3 years. (The first Darkchip4 projector just started shipping - InFocus'es IN83 1080p projector (being reviewed 7/2008). We haven't seen the DC4 in action yet, so how good it really is, I don't know as of the date of this article. But, the DC2 home theater projectors basically claimed 2000:1, or more commonly 2500:1. The DC3 projectors though, often claim 3500:1 up to 7000:1.
In the LCD camp, the first home theater projectors were at best 1000:1 or 1500:1, so their black levels were no match for the DC2 projectors nevermind the DC3s. By the time the DC3's were shipping native 3LCD projectors without dynamic irises and other tricks, still really couldn't hit 2000:1. BUT - and it's a big BUT: it's been probably at least three years since any serious 3LCD home theater projector has been without a dynamic iris, so all of a sudden we start seeing 5000:1, 10000:1, and this year even 50000:1 claims. Those claims though are based on dynamic irises, and the numbers are misleading enough as to be pretty much worthless. If one 3LCD projector claims 10000:1, and another claims 15000:1, I wouldn't expect the one with the better number to do a better job than the other, in black levels.
And, now with DLP projectors widely having dynamic iris or lamp dimming, or other enhancements, their numbers are just as uninformative. When it comes to LCoS however, JVC stands out. Not only does their best under $10,000 home theater projector have the best black level performance around, but they do it straight - no irises, dimming lamps, etc. JVC has redesigned their LCoS chip to generate better true contrast than any of the other technologies can match. Even their last year's model is still #2 out there, behind the new JVC - the DLA-RS2. The older one, was the RS1, which I'm still using. Sony's two LCoS projectors, the VW40 and VW60, on the other hand, with similar contrast claims, relies on dynamic iris technology to get the best black levels they can. The Sony's are excellent bested by only one or two other projectors, but they can't match either JVC.
For that reason, LCoS is king of the hill right now, with the JVC doing it all, without gimmick, and Sony pretty much right behind them, but using the same gimmicks as just about everyone else.
Next in the pecking order comes the Epson Home and Pro Cinema 1080UB, the best of the 3LCD, and it is every bit the match for the Sony's but also comes up short against the JVC's. None of the other 3LCD or DLP's that I've seen, can match the Epson's performance but several of each technology come close.
"OK, it's got a dynamic iris - so what - doesn't the iris get the job done?"
The answer is: "Not really", or "Not as well as one would think" At this point I'll drop in a link to an article discussing dynamic irises, AI, dimming lamps etc. (Sadly, that article is still in the works, but a link will be added here shortly.
Bottom line: With almost everyone using dynamic irises, etc., no one technology really wins the quest for the "Holy Grail". That said, at this moment if you want the best, it's JVC's LCoS projectors, but the best of the other technologies are not that far behind. If I was losely grading, let's say the best JVC rates a 90, the other JVC and the Sony's and those UB Epson's are all getting 85 or more. Many others are in the 80-85 range, and nothing these days below 70.
Now, using the same scoring, if we were shopping three years ago, a few DLP projectors would have been in the 75-80 range, and none of the LCD's would have scored over 70. Now that's a lot of improvement, and, as a result, the quest for black levels isn't as big an issue for the hard core enthusiast as it was a few years ago. Other factors are therefore getting more attention.
Once again, there are some general trends - for the most part, the 3LCD projectors are the quietest, but not all are. The Epson Cinema series home theater projectors are fairly noisey in high lamp brightness mode, although still not quite as noisey as the average DLP. The quietest 3LCD projectors - models from Panasonic (that PT-AE2000U just mentioned above), Mitsubishi and Sanyo, are extremely quiet, in most cases making noticeably less audible noise with lamps on bright that most other projectors can do in their dimmer, "quieter" low lamp modes.
The quietest of projectors claim 18db to 24db in low lamp mode, and typically 4db to 6db louder with lamp on bright. Most of the remaining 3LCD projectors (other than those mentioned in the paragraph above, still manage to stay around 28db to 31db with lamp on bright.
Most DLP projectors are 28db - 32db in low power and 30 to 35db in full power. The LCoS projectors vary, but are still typically at or under 30db with lamp on full. Again, there are always exceptions. Those physically large BenQ DLP's are moderately quiet. The big boxes make it easier to dampen down the sound, compared to most DLP projectors which are anywhere from half to less than a quarter the physical size.
But, let's get practical here - audible noise is very tangible, so what is acceptable? Some folks are noise intolerant. They are unhappy if they can hear the fan softly, even if a scene is completely quiet. Most of us, however are more tolerant. For the vast majority, any projector doing 30db or less in full power is strictly no problem, and depending on how close the projector is to the seating, even a little noisier. Fairly noisey projectors like many of the DLP projectors, though, are unacceptable to those most concerned. As another reference, I would guess that those of us with central air conditioning or hot air heat, probably hear 33 to 40 db of mostly fan noise, coming out of your heating vents. Let me put some numbers to what should work for you:
I'd guess 98% of home theater projector buyers have no problem if a projector claims 30db or less, and probably 90+% can live with 32-33db. After that, though, it drops off quickly - few would consider a projector doing 35+ db to be acceptable.
When I discuss image noise here, please realize there are many types of "noise" including motion artifacts, cadence noise, and so on. Here, however, I'm speaking of basic image noise. when you are looking at a image without much movement, you can usually spot a little noise in the picture if you are looking for it, just as you can notice the film grain in the movie at the (non-digital) theater. Most projectors also have several noise reduction options.
Overall few projectors have enough basic noise in the picture for it to be an issue, but there are exceptions. DLP projectors tend to have a little more noise, (no, I don't know why). Once in a while it shows up at levels which can be easily noticeable. Our recent review of the BenQ W5000 discovered the W5000 to be very image noisey, enough that I felt that it would be real problem for some. They have since updated the firmware, and it's a little better, but still more than desireable. They say future firmware releases should solve the problem. It turned out to be the biggest weakness of what was otherwise a superb projector.
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This section isn't about which technology has the brightest projectors, none of these technologies offers any "real life" advantage, however there are some attributes worthy of reflection.
First, most home theater projectors with lamps on bright, produce 250 - 600 lumens in their "best" movie mode. Most typical is around 350 - 450. 350 to 450 lumens is enough brightness for good movie watching on a 100" to 110" diagonal screen (of standard screen materials). In low power figure about 20% less bright.
Most of us need at least two different brightness levels. One mode for a fully darkened (or as close as you can get) rooms for the best movie watching. A second mode though is also needed for dealing with more ambient light. The best example is that if you decide to put on some sports, and invite friends over, do you really want to watch the Game, in a "Cave" - a really dark room? Few would. For that reason projectors come with multiple modes - a "best" mode, usually the dimmest, with names like Cinema Mode, or Theater Black 1, or Movie... You get the idea. They typically have other brighter modes a click away, with names such as Living Room, Dynamic, TV, Family Room, Bright Mode, etc. Generally you sacrifice perfection for more lumens (brightness).
And this is where the differences come in.
3LCD projectors usually have a huge difference in brightness as they go from their best to their brightest modes, sometimes they will get as much as four or five times the brightness, and almost always, at least double.
With most DLP, and LCoS projectors however, the differences aren't as great. My own JVC RS1, for example, going from best, to brightest, gets less than a 20% boost, and that seems to be pretty true for LCoS home theater projectors in general. DLP is more varied in range (far more models) but rarely will you find a DLP projector that can produce more than double the lumens in brightest mode, more typical is a 25 - 50% increase.
Sounds like those 3LCD models make the most sense? At first glance yes, they have sufficient brightness to handle good sized screens in best mode, and the most muscle for that Sunday football game with some lights on.
The catch is this: DLP and LCOS projectors are typically at least as bright in best mode, as 3LCD, and typically significantly brighter. Therefore: DLP projectors are typically brighter in best mode, and not as bright in brightest - another trade-off for your consideration!
Whose got the brightest out there. In the 720p world, the champ is the Panasonic PT-AX200U, but Epson's Home Cinema 720 isn't too far back, and Optoma's new HD71 DLP is in the same ballpark as the Epson when comparing brightest modes, but easily brighter in best mode. That Panasonic, BTW, almost reaches 3000 lumens at its very best.
In the 1080p world, Consider my JVC with over 750 lumens in best, and 900 at brightest, compared to, say the Epson "UB" with just over 450 lumens at best, but over 1600 at brightest. Optoma's HD81-LV, though is the champ, under $10,000, putting out almost 1500 lumens in best mode. The Optoma's really don't set up a mode for maximum brightness, but I set up a user mode for the purpose, and felt that depending on the amount of sacrifice of picture quality, I could still get a very watchable image at 2600 lumens, and a better one that's around 2000 lumens. (As you see, still less than 2:1 between dimmest and brightest). InFocus has a very bright DLP, the IN82 (and the new IN83 as well), but that Optoma still has a brightness advantage. The IN82 mustered up 1228 lumens, and just over 1700 in brightest mode. Close, but 2nd place. On the other hand, that Epson Home Cinema 1080UB, that I consider the best of the 3LCD projectors, could do 1665 lumens in brightest, but as mentioned a mere 468 lumens in best mode. Tsk, Tsk!
Bottom line on brightness - comes down to what you watch. If you are strickly movies in a dark room, and don't have to worry about sports, etc., The LCoS and DLP projectors tend to have more "best" lumens. If you watch all kinds of stuff, in different lighting, though, the 3LCD projectors may be your ticket, or, one of the "light canon" DLP's like the InFocus and Optoma mentioned above.
Motion blur - this is a new "issue" and a very minor one at that. Some folks say they can notice the slower speed of 3LCD and LCoS compared to DLP on some fast action scenes. I, personally don't find this to be an issue, although, it will be for some, I'm sure (there's always someone...). Thing is, the motion blur, at its worse, is minor, and it wasn't on anyone's radar until projectors started getting rid of 3:2 pulldown in favor of direct 24fps support, on movies. (The 3:2 pull-down method used with movies, inherently makes all images a little jerky, something we've all lived with for years, until very recently). By comparison, motion blur is insignificant to 3:2 pull-down jerkiness. (Hope that helps!)
So, after all that, which technology will work best for you?
Summary: Which Projector Technology Works Best For You?
Easy, it's not about the technology - all are capable of great performance. Each technology may have certain strengths or weaknesses, but no one technology has it all over the other two.
So, don't worry about the technology, only what works best for you.
So, figure out what you are watching, when you are watching it, and what's most important. As usual no one single technology wins hands down, but as you can see, depending on your needs, one technology may have more projectors that will work for you, than another will. Better to create your short list of projectors that meet your overall requirements, and narrow it down from there.