[Joseph Clark]

I don't know if this idea has been presented before, but it is prompted by the volumes written here about rainbows. I stumbled across a method for seeing rainbows that should allow almost anyone who CAN see them to see them, no matter what the subject matter on the screen. Up until recently, rainbows were a serious problem for me, so I know the phenomenon can destroy the home theater experience for a lot of people. Better to know now than to find out later, after a purchase. If you've never seen a rainbow, and are afraid seeing them will somehow spoil the technology for you, read no further.


I've always seen rainbows on DLPs and the first generation DLPs drove me crazy. I just bought a Sharp 9000 and the effect is dramatically improved on this projector, but it is still there, just not enough to make it a deal breaker for me anymore.


I walked into the room the other night about midnight and glanced toward the projector lens as I prepared to take my seat. As my eyes played across the light coming from the lens, I saw perfectly formed red, green and blue rainbow squares. It so happens that the subject on the screen at the time was a very dark scene - no bright objects in the picture to give away the presence of rainbows from looking at the screen directly.


I have to warn everyone not to look at the projected image this way for ANY prolonged length of time, even a few seconds! You could damage your eyes. Just let the eyes scan across the projection lens of the DLP projector. If you are susceptible to rainbows, you should be able to pick up on the RGB squares very easily. Those of us who can see rainbows on the screen experience the same thing with more brightly lit areas of the screen as our eyes move from one point on the screen to another during a scene. The rainbows that result can and did destroy for me the effect of watching movies on DLP projectors before the Sharp and similar PJs. I can live with the effect now, but I understand those who still cannot. I look forward to the time when this technology can eliminate the effect altogether.


Hope this doesn't repeat someone else's experience already, but if it does, it bears repeating. Hope I didn't spoil anyone's viewing experience.

 

[Mark Hunter]

Hi Joseph,


A similar experience caused me to have to sell my DLP as well.


For better or worse, I'm a bit of a "high-end" tweaker. Picture a tripod-mounted colorimeter connected to a laptop, legal pad notebook and a pen and you have the idea.


Try standing in front of a DLP projector (any single-chip will do) and take notes on a pad of paper by only the light coming from the projector to illuminant the pad. It's guaranteed to make you physically sick in no time.


This doesn't happen with CRT, LCD or LCOS projectors, though.


I know, I know...this isn't the "normal" way that the projectors are used, so you can discount this to the degree that you wish, but the rainbows are certainly there. Anyone who claims that they are not can easily prove it to themselves.

 

[Joseph Clark]

Thanks for the response, Milori.


I want to make it clear, however, that I love this Sharp 9000. Whereas the previous generation of DLPs almost made me sick, I can live quite easily with the rainbows this PJ produces. I've read several posts in this forum that seem to imply that rainbows are an overblown negative of DLP and that people who complain about them are just nit-picking. The main point that I am trying to make is that people react in different degrees to DLP rainbows. I just wanted to provide a simple technique that anyone can use to spot them easily and then use to help determine their own particular degree of susceptibility to the effect.


I envy those who never see rainbows - I wish that was the case with me. When all is said and done, though, the effect is dramatically better with this new generation of DLP and there are extended periods of time when I don't notice them at all. I think there are a lot of people who fall into that category. And the advantages of the technology far outweigh any negatives I've encountered.

 

[Paul Hayward]

Hi Joseph,


In a previous thread I also suggested a similar method to this as a way of seeing the rainbow phenomenon. Observing the artifact at the lens sensitises the viewer to the rainbow effect. They know what to look for. Then quickly moving the eyes away from light sources such as headlights or burning torches on screen drags the light across the screen creating the rainbow effect. Fortunately, I now rarely see rainbows on my HT300, but they are still there and they do crop up from time to time.


Best Wishes,


Paul H

 

[DanHouck]

Every first-generation DLP drove me nuts with rainbows. So I was pleasantly surprised by the Sharp 9000. I watched some heavy action scenes from "A Knight's Tale" fully expected to be rainbowed big time. I moved the eyes around and did the usual tricks, without seeing any rainbows.


Since it is unlikely I have somehow been miraculously cured of rainbow sensitivity, the logical explanation is the faster colorwheel does the trick, at least for me.


Mark, have you had the opportunity to test your rainbow sensitivity with the new DLPs yet? What was the result?


Dan

 

[MichaelZ]

Dude, that is BS! No one should look into the lens of any pj! Sure it is strobing but that is not what rainbows are about. I can see rainbows as well as anyone but I have not and can not force myself to see rainbows on my Marantz (unless looking into the lens). Put in any fast moving black & white movie and this should show all the flaws you need to see. I do not recommend anyone to look into the lens of their pj - you might suffer retina damage!

 

[Joseph Clark]

Not quite sure how to respond to that one, except to say that it's a little over the top.


First of all, I don't want anyone to damage their vision. I warned against that in the post. I didn't mean for anyone to look directly into the lens, and certainly not for ANY extended period of time. You can stand off center and pick up on the RGB patterns quite effectively. And those RGB patterns are precisely what rainbows are all about, just at the lens instead of on the screen surface.


Not to put too fine a point on it, but if "no one should look into the lens of any pj," how do you know you cannot see rainbows on your Marantz "unless looking into the lens."


This post was for simple informational purposes, especially for those who are new to the forum or for those looking for a way to spot rainbows easily. Some people have trouble spotting them, in color or black and white films. Observing them at the lens means you don't have to worry about the subject matter.


As Paul says quite well above, the method simply sensitizes the viewer to the effect. Better to become sensitized to it early on while shopping for a projector than to discover it after the projector is installed.


The BS comment was unnecessary.

 

[Alexander]

Here's another way I found: Put your hand between you and the screen with your fingers spread wide, kind of like you're doing a goofy wave at the screen. Wave rapidly. See rainbows.


Alex

 

[Jim Scarbrough]

Personally, I like to shoot DLP projectors directly into my eyes late at night while driving down a darkened road. I've gotten headaches AND chipped teeth from DLP's this way. And I've got these funny little arched indentations in my forehead....


Boy, glad I found out before I actually bought one!!!

 

[Shawn O]

Quote:

Here's another way I found: Put your hand between you and the screen with your fingers spread wide, kind of like you're doing a goofy wave at the screen. Wave rapidly. See rainbows

waving a pen/pencil will do the same thing.Just a lot easier

 

[LMDA1]

Funny this thread should pop up. Last night while watching "Ali" I glanced above me where the projector is and I happened to look at the space between the Panamorph and the lense, there it was in all it's glory:the rainbow. This time I could see large "pieces" of color strobe. For a few seconds I played with my eyes and each time it was clear as can be. Then I turned to the screen and got lost in the image and sound. What a great hobby !

 

[BGPGuy]

Ok I am staring into the lens. I think I see it,yes, I aaaahhieeee!!! Oh sweet Jesus my eyes! My eyes!! Maybe if I flush them with windex, yes, that is doing it no NO AIIIEEEGHAH!! Ah Ah Ah!


Thank you AVS Forum! Next week we will discuss how to check for proper voltage to your video equipment with a coat hanger and loose boxer shorts!

 

[David Mendicino]

Ah Ha!


YOu may remember my posts about rainbows from a while back, when I had more time to post.


First things first,

about a year or so ago, I mentioned this exact phenomenon with respect to the seleco HT200, that is, if you look near the lens of the projector...you can see the rainbow effect. Oddly, nearly a year or so later, someone else has brought this up....not that I mind...

Secondly, as you may note that I have a very high sensititivy to the rainbow effect, I can see it on the Sharp9000 quite readily at a certain distance.


When I don't see the rainbows, I still feel that there is something incorrect with the image....like it is about to break up...hard to discribe, nevertheless, present.

 

[Joseph Clark]

Sorry I haven't posted in the past couple of days. Glad to read the thread has gotten so many interesting responses.


Sad news, however - I now have to have this post typed for me. First, I broke my right hand while waving it violently in front of the screen trying to see rainbows. At lunch the same day, I got a third degree burn on my other hand when I touched the soup plate, even though the waitress warned me it was HOT! And last night I went blind staring into the lens of my Sharp 9000.


The good news is, I can't see rainbows anymore.


It's been fun. Out.