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Rainbow effect

jonrud

Active Member
I have had two DLP PJs and have never seen the RBE could someone explain what this is and what you see?????????????
 

sdb123

Distinguished Member
You'd know it if you suffered from it. ;)

Do a search in this forum for 'rbe' and look through the (many) results.
 

Member 55145

Distinguished Member
basically you see a rainbow outline to anything that moves on screen, and if you move your eyes you get a flash of colours. its very disturbing and nausiating
 

Avi

Distinguished Member
I have had two DLP PJs and have never seen the RBE could someone explain what this is and what you see?????????????

It a physiological phenomenon hence the reason it varies from person to person in a similar way as "sample and hold" motion smear affects LCD/LCOS based techs.

Certain display technologies i.e. CRT, single chip DLP depend on something called persistence of vision to create the illusion of a complete image. The actual image is made up of very fast moving elements i.e. scanning beam in CRT, colour wheel/mirrors DLP so in reality at any one point in time there is only a part of the total image being displayed but persistence of vision causes the brain to "fuse" everything together and make a complete image. The point at which our brain is able to fuse the fast moving elements together is called a fusion flicker threshold. This threshold varies from person to person with some having a trigger point that may result in them seeing flicker on CRT displays or colour break-up aka rainbows (because there is a very brief flash of red, green and blue) on single chip DLP's. Some people claim they see similar issues with plasma displays or flickering in fluorescent lighting.

Not all single chip DLP's use the same type or speed of colour wheel so it's possible to see the phenomenon on one DLP PJ but not on another. Faster RPM and more primary segments on the colour wheel help reduce the trigger point. In the near future laser light source should eliminate the need for a colour wheel with single chip DLP's.

AVI
 
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rocsen

Standard Member
Count yourself fortunate mate.:thumbsup:

Headache central for me,and many others.:thumbsdow

I think the previous post is spot on, depends which make/model DLP you go for.
I'm totally new to PJ's but I was fully aware of this issue before I bought a DLP. Just did a bit of research to find out which models show this minimally, and it paid off.
 
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KelvinS1965

Distinguished Member
I think the new range of DLP projectors have a new chip that eliminates the rainbow effect altogether.

Not neccesarily so as a recent review in HCC of the Infocus IN83 with DC4 chip said they still noticed ranibows due to the extra contrast of this chip. :( If you see them, then it is a no go...just don't go looking for them. ;) The JVC HD750 is a good alternative if you have the money ( and the time to wait for availability) from what I saw last week.
 

martian1

Well-known Member
Yes.. they are 3 chip m/c's [extra 2 chips] :rotfl: and they cost about 10 times the price. Unless the colour wheel is taken out you will never get rid of it. I have a DLP and its not bad for me either i believe both LCD and DLP have downsides and are comparable or equal on a budget level. For me i hate DLP for noise and not being as sharp as LCD but i hate LCD for not being cinematic enough [looks forced] and dust issues..colour uniformity etc.
I am tormented with the idea of switching from a 720p DLP to a 1080p LCD and if the newer LCD higher resolution pj's are now on a par or better for the same money, in otherwords would a 1080p LCD cancel out some of the negatives that made me go for DLP in the first place. I can get a excellent 720p DLP for less than £1000 or a very decent LCD 1080p for around £1200.
Cannot decide :rolleyes:
 

Avi

Distinguished Member
Not neccesarily so as a recent review in HCC of the Infocus IN83 with DC4 chip said they still noticed ranibows due to the extra contrast of this chip. :( If you see them, then it is a no go...just don't go looking for them. ;) The JVC HD750 is a good alternative if you have the money ( and the time to wait for availability) from what I saw last week.

The Infocus IN83 uses a relatively slow 4x (7200 RPM) wheel. Look for products that offer true higher wheel speed i.e. 10k-11K RPM with double primary segments on the wheel. :)

It's a compromise with the different techs as after owning a JVC I didn't like the sample and hold motion smear.

AVI
 
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Avi

Distinguished Member
I think the new range of DLP projectors have a new chip that eliminates the rainbow effect altogether.

Not necessarily. For example some new PJ's employ a brilliant colour wheel that reduces the number of primary segments by replacing them with cyan, magenta and yellow (RGBCMY). This halves the colour refresh rate for a given RPM compared to a RGBRGB wheel. Some of the new PJ's also still use relatively slow RPM speeds and again this can be a factor in RBE.

AVI
 
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rocsen

Standard Member
Yes.. they are 3 chip m/c's [extra 2 chips] :rotfl: and they cost about 10 times the price. Unless the colour wheel is taken out you will never get rid of it. I have a DLP and its not bad for me either i believe both LCD and DLP have downsides and are comparable or equal on a budget level. For me i hate DLP for noise and not being as sharp as LCD but i hate LCD for not being cinematic enough [looks forced] and dust issues..colour uniformity etc.
I am tormented with the idea of switching from a 720p DLP to a 1080p LCD and if the newer LCD higher resolution pj's are now on a par or better for the same money, in otherwords would a 1080p LCD cancel out some of the negatives that made me go for DLP in the first place. I can get a excellent 720p DLP for less than £1000 or a very decent LCD 1080p for around £1200.
Cannot decide :rolleyes:

Not entirely true. The IN78 has a darkchip3 with 4x colour wheel. Costs £800
And as I said before. I cannot notice rainbow on this PJ at all.

I watched Cloverfield this evening, and if there's any movie that will show rainbow, it's that one.
Didn't notice a thing.
 
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jonrud

Active Member
So has I have not notice it with both of my PJ the chances of seeing it on another PJ is pretty slim hopefully or not at all?.
 

GaryB

Distinguished Member
So has I have not notice it with both of my PJ the chances of seeing it on another PJ is pretty slim hopefully or not at all?.

If you haven't seen it so far, then the chances are that you aren't sensitive to it, so you will probably be OK with a modern DLP. This is by no means guaranteed though, so you really should try to audition the models you're thinking of buying.
 

Avi

Distinguished Member
So has I have not notice it with both of my PJ the chances of seeing it on another PJ is pretty slim hopefully or not at all?.

As with any PJ tech it's better to see the product you intend to purchase first hand. :)

AVI
 

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