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The dreaded "Rainbow Effect"

Discussion in 'Projectors, Screens & Video Processors' started by Nick_UK, Dec 31, 2004.

  1. Nick_UK

    Nick_UK
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    Over Christmas we had the family over, and we watched a couple of movies on my Benq 6200 projector on a screen measuring about 87" on the diagonal. The first movie (their request, not mine) was "Love Actually", and the second was "The Day After Tomorrow". The age of the audience ranged from 26 to 76, seven people in total. I didn't mention the rainbow effect, or potential eye-strain - we just watched the movie.

    Everyone enjoyed it. Nobody mentioned rainbow effects. Nobody complained of eye-strain, or dizziness or headaches.

    I sometimes wonder if we don't all hype ourselves so much into the advantages/disadvantages of our technology, that we have become incapable of properly enjoying it ?
     
  2. PJTX100

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    Excellent. Glad everyone enjoyed the films. I think modern PJs are great whatever the technology. However, rainbows aren't a myth, they aren't a hyped up technology-figment of our imagination. And they can affect a proportion of viewers to greater or lesser degrees.
    It isn't a dig at DLP, just an aspect of the technology which shouldn't be ignored....PJ
     
  3. LV426

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    Not a very large statistical sample. There's no question that different people are affected to differing degrees, varying between "not at all - what is it anyway" to an instant feeling of discomfort later followed by eyestrain, headach or even nausea. And the latter are probably a fairly small proportion - maybe 10% of the populus (a total guess with no real basis).
     
  4. martian1

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    accepted but if it was explained beforehand...Woh :eek: ... rainbows city!
    shown how to see them start trying to enduce it and it can be a problem. Otherwise i doubt it is such a big deal, anyway lcd seems to cause quite a few headaches as well :D :rotfl:
     
  5. PJTX100

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    You're missing the point. It is a big deal, to some people.
    The only headache LCD projectors have caused me is one of excitement when I realised how good they were for the price. :rotfl: . :D :rotfl: ..PJ
     
  6. MikeD

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    The rainbow issue has gotten blown up out of all proportion due to the almost daily adverse posts on the subject.
    Sure if you are one of the minority that is seriously affected then you will have strong feelings and probably post accordingly to warn others.
    Unfortunately it tends to give an unbalanced impression as apart from Nick UK just how many people ever bother to post that they don't have a problem with rainbows, it just isn't news is it?
    Like me they're too busy enjoying the great picture that DLP gives, if rainbows were that much of a problem DLP projectors would be on the decline instead of gaining in popularity.
    Like Nick UK I've had loads of friends and relatives around and had no complaints or headaches as of yet, just the usual jaw dropping amazed looks on their faces and cries of is that all it cost.
    To those reading who are thinking of buying a projector and are confused by it all be sure to demo both DLP and LCD, chances are you will go away wondering what all the fuss was about.
    For good budget DLP projectors try Optoma's H30 and their new H31 or Infocus's 4805.

    Regards, MikeD
     
  7. martian1

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    OH...No you are missing the point , i ain't got a problem with LCD its lovely on my camera otherwise ...cartoon vision......... :thumbsup:
     
  8. cyberheater

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    We just had 3 friends over to watch a movie and no one complained of rainbows or headaches.

    I do believe that a small vocal minority is blowing it out of all proportion. Maybe they can't believe that it doesn't affect other people the same way it affects them.

    I also do sympathise with them and I do feel that dlp manufactures should carry some sort of warning for those who might be affected.
     
  9. Sigismund

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    I don't understand this "rainbows have been blown out of proportion" sentiment. Recently I had been prepared to spend up to the cost of a Sony HS50, and decided to demo that PJ against the Mitsubishi HC900. I would most likely have bought the Sony "blind", but I wanted to see how a DLP around the same price compared - and I would not have bought a DLP without demoing first because of the advice gained here. I actually preferred the HC900 image, but the noisy fan and, more importantly, a case of eye strain had me choosing the Sony. I don't see why you'd have to be seriously affected, either - I didn't feel the effect was particularly serious, but it would definitely have adversely affected my viewing.

    Surely the best course of action, once you've read about eye strain/rainbows/vertical banding etc., is to demo any PJ that you/your family are interested?

    So thanks to everyone who pointed out that eye strain and rainbows can be a problem for some people - I would not have enjoyed forking out around £1600.00 only to discover that I couldn't enjoy my new toy!

    Similarly, thanks to everyone for pointing out the foibles of LCD PJs, it's made my choices sensible ones... I think! :smashin:
     
  10. franc

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    Just a thought......maybe they did see rainbows/visual anomaly but either didn't know what they were seeing or were reluctant to indicate so. I know for sure, I would find it hard to draw attention to a caveat on a close friends equipment without offending them. That's just me, I guess....

    regards FRANC
     
  11. Oakleyspatz

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    The problem with rainbows are once you've seen them , you KEEP seeing them. The problem with continually drawing peoples attention to them here and elsewhere and detailing exactly how to see them just induces more people to see what they otherwise may not have noticed. It's a bit like pointing out to someone a nasty stain on their wall, they may never have noticed it before you mentioned it, now they see nothing else. I own an Infocus SP4805 and for the first month of ownership, never once noticed any rainbows. After reading on here just how to induce them, I now find myself shaking my head from side to side to see these rainbows instead of enjoying an otherwise superb picture.
    Let's just advise people to demo before buying and leave it at that, otherwise we may run the risk of turning a few isolated cases into an epidemic !!!
     
  12. PJTX100

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    The thing about winging about imperfections in the technology is that manufacturers start to take note and do something about them. Which is why LCD and DLP have improved over recent years. If no-one had mentioned rainbows then they wouldn't have tried things to improve this aspect, and it could be that some people who are happy with DLP today wouldn't have been otherwise. So actually you should be thanking this vocal minority!
    Happy new year to you all! :hiya:
    ...PJ
     
  13. Nick_UK

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    What you are saying is true. I'm sure that a few people must have observed the rainbow effect, but the point was that nobody let it spoil their enjoyment. I think that the problem with many of us is that we spend so long looking for rainbow effects, dead pixels, dust on the lens, (etc) that we become obsessed and we don't enjoy the product.

    Also, people are very suggestible. If you were to open a new theme park ride which was so mild that even your granny could ride it, but warn people before-hand that the ride could cause nausea and sickness, you could be sure that 50% of the people who rode it would feel ill. It's called mild hysteria. Similarly, if one person on a forum suggests that watching a DLP projector can cause nausea and headaches, you can be sure that others will suffer from that too. How many people had problems with DLP projectors before they knew of these effects ? I must admit that I have sat through countless company presentations on DLP projectors, but never saw any problems until I had been made aware of their existence.
     
  14. Louis Mazzini

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    I agree that the rainbow effect itself is blown out of proportion, but it is vital to understand that it is not these irritating little flashes of spectral spectrums themselves that upset us sensitive types: It is the very nature of the single-chip colour wheel DLP. These machines work, as I understand it, by displaying a red image, then a blue one, then a green one, mixed not in the projector, but in your brain. Some of us have brains that are too fast/too slow for this to work without problems.

    Having looked at (and been keen and ready to buy) several high quality (albeit all single-chip) DLPs last year, I soon realised something was very wrong. Yes, I could probably live with all those little rainbows, but there was something else... Coming away from every screening it was always immediately obvious that looking at an LCD/Plasma/CRT screen afterwards was vastly more comfortable and relaxing. Why was this, I wondered. In all my research in magazines I had not seen an explanation of this. What the hell was wrong with me, and was I alone..?

    Over the year I auditioned projectors with four friends, also all keen to buy and, how odd, they all suffered similarly. Where was the magazine article about us?! Were all five of us in the “unlucky 10%”? I have another friend who already has a DLP (a good Sim2) and he has reported no problems. (I don’t mean to enrage anyone out there, but I do sometimes wonder if there’s perhaps a little bit of denial going on with the people who already paid for their machine...)

    So, the bottom line is, for some of us, DLP is just too uncomfortable to watch. However many segments they’ve added to the colour wheel, and however fast they’ve spun the damn thing, it’s still a horrible viewing experience. Great blacks though. From my experience, I’d say it’s a fact that magazines deliberately ignore this major problem with DLP. The reason I’m vociferous against the technology is to let people know that it’s crucial to give it an extensive demo before purchase; if you’re okay with it then good luck to you (and all those you invite round...).

    Anyway, a Happy new year to you all and, for a change, I can’t blame today’s headache on Texas Instruments..!
     
  15. Nick_UK

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    Did you warn your friends of any potential problems beforehand ?

    As you can see from my sig, I own a 42" plasma TV, and a Benq 6200 projector, and I'm more than happy to watch the dross that BBC, ITV and Sky push at me during the week on that, but when I have a decent DVD to watch, the projector comes out. To be honest, I would watch the projector even more often were it not for (a) the price of the lamps and (b) my projector setup does not lend itself to everyday usage.
     
  16. Louis Mazzini

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    Fair point. Two knew all about it; two were pretty much newcomers (and yes, perhaps I was wrong to warn them about rainbows and eystrain). So, fair enough, if I hadn't mentioned it, maybe they wouldn't have experienced it ...but then again maybe they would have silently wondered what was wrong. I, perhaps selfishly, really wanted to know if they thought something was wrong though, because I was beginning to think the problems I was noticing with DLP were being hushed up (I still do)...

    I do take your original point though: If the picture looks okay, don't fuss. Then again, when your family were dazzled (in a positive way!) by your Benq over Christmas, as well as not mentioning rainbows, did any of them mention any disatisfaction with contrast, black levels, colour saturation, etc? I doubt it. Now, I'm not saying your PJ suffers badly in this area, but it could no doubt be better all round, as all of ours could be. The point is, your family weren't like us lot: As far as they were concerned, the picture projected was presumably just the way it should be; the trouble is, we all know "better" than that..!
     
  17. pantages

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    I agree! For the price we pay we get excellent value. Why hunt down any possible artifact when really you are seeing a superb picture that is appropriate to the cost of the machine? If you want to see a 'fault' then you will see one, but the point of owning a projector is to enjoy it. Even In the cinema you will find faults, especially distortion and poor contrast or colour.
     
  18. Bristol Pete

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    There are some interesting points here - its a great post. I concur with the fact that once we have read about or established a fault we all go looking for it rather than enjoy the machines we all own.

    However, surely its not exclusive to the projector scence. Refer to other threads here, even within the DVD player, DVD disk threads and so on people are looking for and highlighting problems and faults.

    I suppose we are all craving perfection within the realms of our budgets.

    However, I am happy to agree that occasionally, some things can be worse than others. Vertical banding for instance.

    Happy new year all!

    Cap :)
     
  19. -TYN-

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    The problem is for alot of people this is no minor artifact or something you have to hunt for. For me personally this is a big problem that i see constantly even with the latest and fastest colour wheels. I believe also alot more people see rainbows than mentioned, all people i show it to all see the problem but at varying levels. I know i had to point it out, but this still shows that they can see it, and if they had the product themselves would eventually notice and be bothered by it also.
    As i have mentioned in other threads i think the picture from dlp is the best i have seen and am prepared to wait a certain amount of time for products containing the scr wheel become available to totally eliminate this effect.
    To call the people picky for being bothered by it is very wrong, ive also got a Sony grand wega rear lcd which has some shortcomings which i would call minor and because they are minor they do not effect my viewing, the rainbow effect is far from minor for me.

    This is just my experience heres hoping a solution comes fast
     
  20. LV426

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    The thing that makes DLP rainbpows important is that, unlike (say)

    - poor geometry or colour registration
    - grey blacks
    - excessive overscanning

    or pretty much any other thing that may have an effect on your image, the DLP rainbow effect, to someone who is sensitive to it, is something you can't get used to, nor tolerate. It's actually a serious issue that you can't get away from..... IF you are affected.
     
  21. GLADIATOR

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    If you don't suffer from "rainbows" you really can't comment on the magnitude of the problem. If you don't suffer then that's great, but don't just tell others its not a big deal. If you suffer you will know about it and it will affect your viewing and enjoyment. For new PJ buyers go test a DLP PJ. If you don't suffer from rainbows buy a DLP. If you do don't worry a top of the range LCD will serve you just fine. And as others in this thread mention just enjoy!
     
  22. junkster443

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    if you want perfection buy a screeplay 777 three chip dlp no rainbows no bad colours perfect blacks and a very silent machine

    thats if you have 20,000k to waste my point is we cannot expect prefection for the small money we have to spend three chip dlps will be much cheaper in the future at the moment they are overpriced and only intended for rich people
     
  23. cyberheater

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    The more I think about it. The more i'm surprised by folk that are susceptible to the rainbow effect aren't affected when they go to the cinema.

    Surely, a film in a film projector is continually getting switched on and off and it's only our persistance of vision that allows us to see a smoothish image.

    Given that the strobing effect at the cinema is a lot slower then the speed of a dlp wheel. I'm surprised that there aren't any folk that are cinema intolerant. Or is it something to do with higher refresh rate of dlp forcing alpha waves out of synch or something like that.

    I wonder if anyone has actually done the research on it to find out exactly the root cause of the condition.
     
  24. Gary Lightfoot

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    That's an interesting point.

    The differences I can think of are that the image is made up of 3 or 6 RGB 'flashes' (depending on the CW makeup) as well as frames, so that might put an extra strain on the eyes/brain perhaps. Cinemas are also putting out around 12 ft lamberts of light from the screen, and at home that is probably much greater, since not many people will calibrate using something like an ND filter to ensure they're not exceeding it.

    It would be interesting to see a proper analasis and conclusion though.

    Gary.
     
  25. PJTX100

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    ...and an everyday CRT TV flickers at 50Hz or 100Hz... must be something to do with the brain being asked to mix RGB together rather than string together motion?...PJ
     
  26. LV426

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    I'm 100% sure that's it. I am refresh-rate intorlerant on regular CRTs but that doesn't induce any ill-feeling; I just don't like it. However the DLP issue is quite different. And yes, I'm sure that there is a huge difference between a full-colour image flashing on and off, and three different colours flashing incessantly.
     
  27. PJTX100

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    By the way, what's the scr wheel?...PJ
     
  28. Nick_UK

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    Take a look at this link

    I wonder if there is a link between colour blindness and susceptability to the rainbow effect ?
     
  29. Sigismund

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    SCR = Sequential Colour Recapture :)
     
  30. Gary Lightfoot

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    That has been talked about for some time now (3 years or more), and it still hasn't been introduced, so I doubt we'll see it any time soon, if at all. We've seen more segments and iris's introduced, but the colour wheel has remained much the same. I think TI gave up on it due to it being too hard to make it work properly.

    There was also mention of an Archimedes colour wheel (probably the same thing) but that hasn't made its way into production either, so other than 3 chips, I can't see the colour wheel as we know it changing much any time soon.

    If they can improve the response of the DMD mirrors so they can switch on and off faster, then we may see faster colour wheels which will reduce rainbows further for those that see them, but currently a faster wheel with more segments seems to reduce DMD modulation range so that has it's own drawbacks.

    Gary.
     

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