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Just witnessed RAINBOW effect on a CRT projector!!!

337 Views 24 Replies 23 Participants Last post by Morbius, Jun 29, 2001

safire

Discussion Starter · Jun 23, 2001

I know this sounds impossible, but my girlfriend and I just saw a sony vph-1271 which had just had the tubes replaced and when flicking our eyes around the screen we noticed the same type of rainbow effect experienced in DLP projectors. Not to the same degree, but they were definately there everytime we looked for them. Just like DLP's it happened more in the high contrast scenes. We have been seriously tossing up between a crt or a dlp projector, but with DLP's having reasonably good blacks and far less maintainence, I can't justify spending so much money on a good CRT projector which obviously should display a better picture, but from what we just saw tonight, I would stick with DLP anyday! I do understand a top of the line CRT can't be beaten on performance for home theatre, but dollar for dollar, a DLP under $5000 (eventhough all projectors have their drawbacks) is far better overall when all things are considered. (long term cost, brightness, portablility, reduced screened door and scan lines).I would love to hear from anyone who has witnessed anything similar to this.

Thanks Steve and Naomi.

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1 - 20 of 25 Posts

fulabeer

· #2 · Jun 23, 2001

I've just had a demo of a Seleco 400 CRT and to my amazement i saw a slight rainbowing effect as well!.

I had just demo-ed the HT200 DLP and thought maybe that was fresh in my mind (i saw rainbow all the time). I waved my hand in front of my face as i did with the DLP to force rainbow but that did'nt cause it. It was just blinking etc that caused the slight rainbow.

The saleman asked what i was doing, and when i told him he was gobsmacked. Stating it was impossible to get rainbow with CRT, to which i agreed. But what was i see-ing?.

He was using a high gain stewart screen that produced sparkles with the DLP, so i was wondering if that was causing slight colour shifts etc during the screen scan etc. Anyway after a couple of minutes the rainbow effect totally disappeared!. This was probably due to the projector reaching full operating temp.

Mind you these days I start looking for panel structure and true black levels even when looking out of the window!, anybody know a good shrink...!

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Nuff said!

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stefuel

· #3 · Jun 23, 2001

Defective ice cubes causes this effect, I know i've seen it before.

Chip S.

kevin gilmore

· #4 · Jun 23, 2001

What you are probably seeing is the difference between

the persistence of the phosphors between the guns.

The red has the longest persistence. Its also possible

the drive circuit is being overdriven which can cause

a similar problem.

Rainbow effects only come on devices with a spinning

color wheel.

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Torre

· #5 · Jun 23, 2001

Were the screens glass beaded? Glass beads can seperate the colors back to the primary three.

I'd be curious to see if the rainbow effect is still present if projected onto a matte screen.

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Mark A. Torre

NEC XG-8"CRT PJ, HTPC, HDTV and loving it! The Torre Home Theater

joelco

· #6 · Jun 23, 2001

Also! Don't forget that the human eye has some persistance and it is far more likely to be that which you see.

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[email protected]

PF

· #7 · Jun 23, 2001

Any pink elephants?

David Mendicino

· #8 · Jun 23, 2001

That is strange timing...I was just watching a movie on a friends sony 61" rear projector that is a few years old, and I noticed some rainbow as well, I thought I was going insane, or that my quest for no rainbow has led me to see rainbows in every TV I see!!!

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David Mendicino

Sharp xv-s55u (Don't laugh)

KBK

· #9 · Jun 23, 2001

it's a perceptual characteristic involving the eye's sensitivity to blue, i'll wager. Wait a minute. are all these units being used to present video signal in the UK? at 50hz?

Anyway, get past the eye's inability to 'lock' clearly on blue, by moving , or flitting my eyes about when aligning blue on green in my PJ's convergnce system. By moving my eyes about rapidly, i can much better 'see' the blue edging, or alignemt errors. If I move my eyes about SLOWLY.. this is nearly IMPOSSIBLE to see. batter yet, switch to magenta....

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goosystems.com

Ken Hotte

[email protected]

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KBK

· #10 · Jun 23, 2001

Ever heard of "Road Rush"? the effect that occurs with your brain/eyes as a sensory combo when you come off of a long highway ride? It can easily take 20 minutes for the view in front of you to stop having minute characteristics (to your current sensory state) that make it appear as if what is in front of you is MOVING AWAY from you.

Were these CRT units viewed AFTER some heavy 'rainbow' loaded DLP images.. that were viewed for a fairly long time? And, your brain/eye combination fighting with you to 'rid' you of the 'noticability' or interference of the rainbow effect? It is NOT in any way unlikely that you brain 'filled in' the missing rainbow effect for you.. Except it would probably be opposite in color balance and effect. If you see it again, look for this. It might be 'automatic masking' created by your sensory organ/brain so as to help you out in your viewing. Basically, the filter effect.(very pavolovian) For instance, have you even any cognizance at all of the fact that you have a blind spot in each eye??? I have played with it on occasion, and realized it , fully, and walked around for days with a dead spot in my vision....(try not to combine this tom-foolery with narcotics, OK?)

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goosystems.com

Ken Hotte

[email protected]

[This message has been edited by KBK (edited 06-23-2001).]

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Curt Palme

· #11 · Jun 24, 2001

Good acid will do that to you every time...;-)

Curt

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He who dies still watching LCD has never seen the light...

KennyG

· #12 · Jun 24, 2001

If you buy DLP based on what you saw with the Sony you are making a big mistake...unless you don't care about picture quality.

Go look at a properly setup crt...there is no comparison.

I have seen DLP, a brand new unit with less than 10 hours on it.It was the worst projected picture I've ever seen...let's see, posterization, no blacks, very flat presentation, no depth at all, rainbow effect.

D-ILA is the only digital projector that even comes close to CRT, it's only down falls are, no blacks (even cal'ed) and less depth to image.

Sean Max

· #13 · Jun 24, 2001

My first response to what you saw would be, as some others have suggested, a high gain screen phenomena. I own a 1271Q, and I do not see rainbow effect, and it is projected on a matte white screen. I have tried looking for it after demoing a few DLP's (that didn't come close to measuring up to my CRT, including the Seleco HT200) and could not find it. I have seen it briefly on my 43" Sony RPTV, but only very briefly and only when I tried to look for it. I attributed it to the fresnel and lenticular layers messing with the light, like that dam halo with bright objects in dark scenes. I have yet to see a digital projector match the picture quality of my average CRT projcetor (though I have not seen any calibrated units owned by members of the forum) and don't expect to anytime in the future. My desire for convenience has not outweighed my desire for a great picture... yet.

I edited my above post to indicatet that I do not see the rainbow effect with my 1271, which is what I originally intended to say. That's what I get for not reading my posts after I click submit (or even before).

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"Experience is the one thing you can't get for nothing." - Oscar Wilde

[This message has been edited by Sean Max (edited 06-24-2001).]

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mp20748

· #14 · Jun 24, 2001

quote:

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"I do understand a top of the line CRT can't be beaten on performance for home theatre"

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True confession!

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Mike Parker

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RobertWood

· #15 · Jun 24, 2001

Mike.

Looks like this continuing debate (CRT vs digital) is

not likely to end soon.

One of this forum's moderators (Laurence) has just carried the DILA ball to within a few yards of the finish line (read "What I liked about Luca's home theater").

Probably the best strategy us CRT devotees could take on this is to just pretend to raise the white flag and surrender. Then others will be discouraged from even considering CRT and we'll be able to buy em even cheaper

(as if they're not cheap enough already). http://www.avsforum.com/ubb/biggrin.gif

Bob Wood

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~ The Sultan of Cheap ~

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Samshort

· #16 · Jun 25, 2001

All I can say is "What you smokin boy"???

No crt projector shows a rainbow effect. That's ONE of the dozens of reasons they are superior to any other type of projector.

rorox64

· #17 · Jun 25, 2001

Talking in terms of rainbow effects, concerning a 3 CRT pj... sounds like a "strange vision" that could have been produced by.... Just kidding!!

In any case, the only things that could be worth to investigate, would have been the lenses (in the Seleco 400 they are the DeltaTacs, totally plastic made and without any color reflection correction) and eventually the usage of an high gain screen for the projection....

this is my opinion.

regards

Romano

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rr25

· #18 · Jun 26, 2001

What you saw was a sign trying to tell you to buy another expensive projector.This happen to everybody on everyday life.It's getting expensive if you think about it.I spent a lot of time testing different projectors but nothing impress me.This can be a problem or a mine illusion.Just thought I can share this to anybody.

Emanuele

· #19 · Jun 28, 2001

Quote:

Originally posted by rr25:
What you saw was a sign trying to tell you to buy another expensive projector.This happen to everybody on everyday life.It's getting expensive if you think about it.I spent a lot of time testing different projectors but nothing impress me.This can be a problem or a mine illusion.Just thought I can share this to anybody.

Which kind of projector didn't impress you ? Have you seen only LCD/DLP unit ? Ever seen a CRT ?

I mean lot's of CRT impress me... but every CRT projector has some kind of defect, little defect (for example one has livid color, another has not so much definition or not so much brightness) but usually with those defect you can live with, and you can watch the movie !!!

With DLP/LCD I think you cannot watch a movie (at least if it isn't a CG) because you cannot live with image flatness, colors out of scale, rainbow effect, non natural motion and dozen others.

I just brought a GP-5000 from Rorox64 which let you see the movie not the projector defects (and it has some defects: low brightness and low definition). But what actually I'm seeing with this projector is the closest image to a cinema ever seen ! This has impressed me, especially when I had 5 minutes of goose bumps watching Dinosaur.

just my 2 cents.

bye

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Emanuele Solazzi
My DVD Collection

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BizarroTerl

· #20 · Jun 28, 2001

I've seen the rainbow effect on my Mits. RPTV very infrequently. The last time was in a fairly static area of the screen that was displaying a sports jacket with a wacky crosshatch pattern. I assumed it was due to the overall poor quality of the set.

1 - 20 of 25 Posts

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