posted 04-30-2009 10:18 AM                    

quote: Julio Roberto

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Don't worry too much about the color wheel.

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posted 04-30-2009 11:35 AM                   

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One study suggested that 2–3% of the world's women might have the kind of fourth cone that lies between the standard red and green cones, giving, theoretically, a significant increase in color differentiation.[4] Another study suggests that as many as 50% of women and 8% of men may have four photopigments

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Some people are never bothered by DLP rainbows. I am one of them. I can watch a DLP projector all day long and never see visual distractions or develop eyestrain or headache. This is somewhat of a handicap for a projector reviewer. In years past I'd give a particular DLP projector a glowing review, only to get a flurry of email saying, "Evan, are you nuts? There are rainbows everywhere."

Individual sensitivity to rainbow artifacts can vary greatly. In addition to folks like me who don't see them at all, there are those who notice them from time to time, but don't find them to be much of a nuisance. On the other hand, there are some who are so bothered by them that they cannot watch a DLP projector under any circumstances.

In today's market, most business class DLP projectors have what is known as a 2x speed wheel. Many units designed for home entertainment have 2x wheels also. It is the 2x wheel that causes the most problems.

Texas Instruments and the manufacturers of DLP projectors have increased the speed of the sequential color updating in order to reduce the percentage of the population that is affected by rainbow artifacts. By using a different wheel design that uses two sets of red, green, and blue filters instead of one, the manufacturers are able to double the refresh rate on the screen. This wheel design is referred to as a 4x wheel, and it substantially reduces the number of people who are affected by rainbows. Our newest staff reviewer, Bill Livolsi, has trouble watching 2x DLP projectors for any length of time. But he has no problem at all with the 4x models.

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I'm the type that can see rainbows on 2x and 4x color wheels easily when I move my eyes rapidly from, say, one corner to the opposite and there is white on the image. If I just stare at the screen from a distance, I can never see them.

Today's color wheels are usually 7 segment and they are 6X speed (10,800 RPM). The refresh rate is tuned to the wheel frequency and thus, I don't think that motion on the screen has any effect on rainbows if TI engineers knew what they were doing at all, which I believe they did.

Fast motion may help to show rainbows as with fast moving objects you are usually inclined to move your eyes rapidly to follow these objects as they move across the screen, but nothing else.

On the other side, if single DLP chip projectors were so bad as to be unuseable, I don't think they would've been selling all these years and new models continue to show up even this year. They would've been scrapped and 3 LCD taken over.

So perhaps is not such a big issue for a lot of people.

Except on Transformers. On that movie, your eyes will be moving all over the screen trying to follow whatever the hell is going on. It's bound to hit a rainbow on a white, high-contrast area for just about anyone

[ 04-30-2009, 02:57 PM: Message edited by: Julio Roberto ]

posted 04-30-2009 11:54 AM                    

quote: Julio Roberto

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Don't move your eyes too much, like when you stare at your TV

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posted 04-30-2009 12:29 PM                   

quote: Julio Roberto

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The alternatives either don't exist or are far more expensive or have other drawbacks.

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And, as I said, the first choice I recommended was a $10k machine that didn't use color wheels and should do a fair job for the task. Given the constrains of the situation. I would also usually recommend using two stacked lcd small projectors over an expensive, single DLP one.

But yeah, before you commit to an expensive color wheel solution, make sure you test it under the closest conditions to your final usage scenario as you can (i.e. a large screen), sitting at close and also at medium distances from it, preferably displaying high contrast material rich in whites (i.e. a black and white movie) and moving your eyes around a lot.

Get 5 or 10 people and tell them to do the same. If you all can sit through the entire movie and not notice rainbows, well, the choice is yours.

E-cinema projectors based on single DLP chips with color wheels abound everywhere in the world, from Australia to China to India, so they must work well enough for enough people.

I guess.

He could also get a pair of these Epsons 6100 (no color wheel) at under $2000 each, put them together and get away with it on a small screen (up to 5m or so).

http://www.epson.com/cgi-bin/Store/consumer/consDetail.jsp?oid=63077379

If needed, you can use a high gain screen. They are in vogue across the USA with digital projectors for 3-D, so they must be OK to use

Don't worry about it. Figure anywhere from $5000 for a projection solution up all they way to $95.000, depending on the size of your auditorium and the quality level you are looking for (in resolution and brightness).

Once you have the films and the money, come back and we'll figure out which thing is the best buy at that point. Just don't forget you'll still need e-cinema servers, perhaps blu-ray or digital tape players, amplifiers, equalizers/crossovers, speakers, lights automation, screen, sound insulation treatments, seats, etc, etc.

[ 04-30-2009, 03:10 PM: Message edited by: Julio Roberto ]