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i now know why some people see rainbows and some do not...

it has to do with how much you blink or turn you head around.

if you sit still and dont pivit or head and you keep your eyes fixed

on the screen you dont see them.

BUT IF YOU ARE A "BLINKER", ARE TWICHY, OR THE NERVOUS TYPE

THE RAINBOWS WILL GET YOU.

i will bet that even those who do not see rainbows would see them

if they started blinkin like crazy and spinnin their heads
 

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I personally find it difficult to go without blinking for an hour! :D
 

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Quote:
Originally posted by snakeman
i now know why some people see rainbows and some do not...

it has to do with how much you blink or turn you head around.

if you sit still and dont pivit or head and you keep your eyes fixed

on the screen you dont see them.
This is NOT correct. I see them unless I stare at a fixed point on the screen, almost as if I am looking through the screen to the wall. Nobody could watch a movie that way. Yes, some people only see them if they blink or move their eyes around. But others see them just attempting to watch a movie in the normal manner. That's why the rainbow problem is such a problem for many people.
 

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JVC NX7 Projector, Draper 132" (2.35:1) Techvision XT 1300x, Panasonic DP-UB420, Zidoo Z9x, Zappit
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When we all viewed 20" tv's, we were forced to sit transfixed and not move our heads or eyes. Today's BIG screen systems actually force you to do exactly the opposite.


Many years ago, I sold the Kloss Novabeam projectors (OK, now I'm REALLY showing my age). Durng sales training for those projectors I heard the term "significant eye movement" for the first time. It was explained to me that a large screen forces the eyes of the viewer to wander all over the viewing area. As a result, viewing on a large screen device became a physically more involving experience than one could possibly achieve from watching a tv. Some people who have never seen a DLP rainbow artifact don't seem to grasp this concept.


Whether a given projector will produce a rainbow artifact that is not acceptable to an individual is something that has be determined on a person by person basis. I own a 3 year old Davis DL-S8. Rarely do I see any rainbow patterns despite the relatively primitive speed of the Davis color wheel. On the other hand, I recently viewed a new Optoma H55 and compared it to the DWIN T1. Both projectors produced obvious rainbow artifacts. I could have lived with the DWIN, but not for $10K. The Optoma was half the price, but gave my wife and I headaches after an hour.


Some have suggested that the faster color wheels on the latest generation of DLP's from Sharp, Marantz, etc will eliminate this problem. Yet I've read a couple of posts from Sharp 9000 owners who are seeing the rainbow artifact.


The question of why some DLP's produce rainbow artifacts that some see and others don't is a question that, for me at least, has not been adequately explained.

Good Viewing,

John G
 

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The rainbow effect will happen to any projector using time multiplexing (aka "color wheel") to achieve full color on a single display engine (DLP or other). The rainbow occurs when a high contrast (white on black maximizes the effect) object moves across the screen OR your eye moves across the screen such that the position of the image of the white oject moves across your retina. Since the Red, Green, and Blue versions of this object occur at different times you will percieve 3 objects (R,G, and B) displaced from each other. Obviously the high the contrast of the scene and the faster the motion of this object (either in the film, your eye motion, or a combination of both) the bigger the effect of the rainbow. I almost NEVER see rainbows in standard day scenes. I almost always see rainbows in sci-fi or night scenes with reflections where the contrast is high

and you get bright objects. I can live with them and have had no complaints from visitors who have seen movies on my DLP.

I know that a new color wheel is soon to be released that although is still time multiplexing the color, the colors are broken into very thin stripes so that different part of the image will be different colors at the SAME time AND the effective time for each color is reduced - both of which should reduce (but probably not completely eliminate) the rainbow effect. Ultimately I think it will probably still both some people (fewer I hope) and others will not even notice a change from older systems. Anybody who has never seen rainbows should load up a DVD with end titles which are white on a black screen - then move your eyes (or point of foucs) from

right to left and back again. If you still do not see rainbows...you must be color blind :)
 
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