Axiom Home Page Forums General Discussion Technical Questions DLP Technology and Rainbows Question

I’m looking at projectors again and there are a few single chip DLP units that are getting some serious praise. In the past, I have intentionally left DLP units off my shopping list because I keep reading stories about these Rainbows that some folks are sensitive to. I'd rather not eliminate DLP before I know if I am sensitive or not this time.... To try and find out if I am or not, I recently spent about a half an hour in front of a DLP TV at Best Buy looking for these rainbows, but I didn’t see any sort of color oddity at all, and definitely did not see any rainbows. If it matters, the TV I was watching was a Mitsubishi 73” Diamond. http://www.bestbuy.com/site/olspage.jsp?skuId=8454745&type=product&id=1183767793279

I am wondering what it is that folks who are sensitive to RBE actually see? I’d hate to spend a few grand on a projector to only get raging headaches.

Mike we've had our 73" Mits RP DLP for over two and a half years and have never noticed the rainbow effect at all, I've tried to look for it but can't find it. I surly wouldn't hesitate for a millisecond buying another DLP or a Mitsubishi set again ... just how thin is the 73" TV you are looking at?

I believe the higher speed color wheels are less prone to this issue. For example, a 2 or 3x wheel is more likely to show the rainbows, then a 5x or higher wheel projector. Also, I'm not sure all people suffer from "Over the Rainbow" issues.

We have a 61" Samsung DLP. In almost 2 years we have never noticed the "rainbow effect". If you didn't see it in the store (especially with the florescent lights), you won't see it at home.

We just bought a replacement bulb but have not used it yet (4500 hours on the original bulb).

When we first got our infocus DLP projector I immediately noticed rainbows. I could see them everywhere. After a couple of months though i had a hard time seeing them even when I was looking. Not sure if everybody gets used to it like I did but like i said now I dont see them at all. An easy way to find out if you see them is watching the credits or something such as that.

I have a ~3 year old 61" Samsung DLP RP too. I've seen the rainbow briefly 2-3 times. For me to see it, I have to move my head left<-> right without rotating, something that rarely happens when watching. I'm still on the original lamp too -- haven't braved the service menu to see the hour count.

I'd kind of written off DLP, but this technology does have me excited:

Audioholics - TI Intros Lamp-free LED DLP Projector

I'm probably a year or two away from getting a projector, so we'll see how this goes.

As for your question, I never saw the rainbow effect with any DLP units I've looked at, but I have to admit I never gave them serious time, since even if *I* don't see the rainbows, I didn't want to have people over for a movie and find out one of them was sensitive. Personally, I'd continue to leave single-chip DLP off my list, but maybe I'm being overly cautious.

Rick,

The Mitsubishi was about 20” thick, or so… It uses LED. I thought the picture was very, very nice. They also run at 120hz. I’m not actually looking for a TV, but that’s the only thing I was able to find with DLP.

So from you guys who do see these rainbows, would it be safe to assume that if I didn’t see any on the TV in the store then I’m safe?

I’m looking to get a new projector in a couple months. The DLP machines I’m considering are:

Marantz VP-15S
BenQ W20000
Planar PD8150

There's no way I can afford a three chip DLP projector.

Modern DLP's are better than older ones, as I understand it. They sped up the color wheel and put more segments on it. Well, at least for RP sets. Just saw you're talking projector, which I imagine is an entirely different ballgame.

higher spin speeds and the insertion of a "white" color segment (which is obviously used to make the color white instead of having to solely rely on the combination of blue, red and green to make white) have all led to a reduction in the rainbow effect.

I notice is occasionally on my DLP projector, but less now than I did when I first bought it. The LED DLP seems almost like a perfect technology, by the way - small form factor, big size, no bulb burn outs...

Hi mdrew,

It's extremely rare for anyone to see a DLP's rainbow effects unless you are trying to see them or have read about them and are curious. Since I write about this stuff, I taught myself to see them when DLP was first introduced so that I could speak to the issue with some knowledge. But in normal viewing I am rarely conscious of them. In my six years with Axiom, I've only encountered one Axiom customer who returned a DLP because his wife was acutely sensitive to them.

As Anthony11 and Cap'n Pickard have pointed out, the newer sets with faster color wheels with more segments have largely eliminated the effects. I have not been able to see any rainbow effects even when I try with the new Optoma DLP projectors.

The LED light engines on the new Samsung sets have eliminated the "problem". Although the red, blue and green LEDs fire sequentially (and they are synced to the DLP mirrors), they do so at such a fast rate that it's impossible to see any rainbows.

Regards,

Hey Alan, I've been forced to be undecided in my choice for an HDTV. I had planned on getting a Pioneer Elite Kuro, but now the Samsung LED has peeked my curiosity. It has a lower power consumption than the plasma, But I have heard about problems in the past with Samsung. Do you know if there has been any reported problems with the LED sets. This might help me to choice one option over the other.
Thanks
Mel N.

Hey Onn. You might try checking out the rear projection forum at avsforum. I found it very helpful when making my decision because there are so many people posting there.

I beleive that Samsung (and a few others) were having geometry issues because they went to a super slim format and the TV bezel was not quite stiff enough for the screen. This is something they may have solved by now.

I basically went through all the threads for different brands and kept track of how many people were having issues. At the time, Sony seemed to have the least.

Thanks Fred I will go to the avs forum and Happy Canada Day.
Mel N.

As I was gearing up to order my Samsung LED DLP (TV, not projector), I read a few complaints of hourglass problems with thin-chassis LED DLP's. I have the same understanding of the problem that FredK does, that the bezel wasn't strong enough and people were complaining of drooping screens.

I also read that Samsung has corrected the problem. It's hard to really say for sure - the nature of information on the 'net, ya know. But I went ahead and took a chance and ordered mine. I'm happy to say that my Samsung 61" LED DLP doesn't appear to have any sag in the frame. The picture is as rectangular is you'd expect. I see no geometry problems. The picture quality is superb.

/Samsung Cheerleader mode
Overall, I'm extremely happy with the TV. No fan noise, low energy usage, no bulb to replace, beautiful picture, and the price is much lower than a plasma of similar size and picture quality. With the LED technology, the only drawback to a DLP set is that you can't mount the TV on a wall.
/Cheerleader mode off

Keep in mind that the LED-source DLP's don't have a spinning color wheel, and therefore there can't be a rainbow problem (that is my understanding, anyway).

I suspect that browsing through more recent posts on avsforum will show whether or not the issue has been resolved. Its an easy one to deal with though. If your set is out of geometry, send it back. Since it is mechanical, it is also an easier issue for Samsung to resolve.

I would have considered the Samsung but, here in Canada around Christmas, it was almost a $1,000 premium to go this route on a 50". When I figured in one bulb change every 4 years for my low level of usage, it wasn't worth it for me.

Samsung has been one of the leaders (along with Mitsubishi) in the DLP field for a long time. I have quite a bit of experience with their older sets and found them all to be quite acceptable, especially given their low price points relative to other technologies. They definitely had detractors in the past, though. Lip Synch issues, rainbow effect, fan noise, etc. have all (it seems) been addressed. You should feel comfortable with a Samsung if you're talking about DLP. Samsung's track record with plasma, on the other hand, is decidedly not the same. Complaints in the past ranged from poor clarity to downright unacceptable black levels.

Nowadays, though, both technologies are fairly mature (LED DLPS, not so sure about those), so the choices are getting easier.

Sooo,I'm in the process of looking around town to see if anyone carries the Samsung LED's so I can compare to the Pioneer and make a decision. Thanks for the input.

Onn, Mitsubishi also has an LED DLP.

That's sorta what I was thinking as well. Unless someone tells you there's a problem, it usually is never noticed. I stared at the DLP TV for quite a while, looking at it sideways, turning my head, off center, center...etc. I didn't see nothing. The only thing I did notice that bothered me was a very slight jerky panning movement. I suspect that is the TV's video processor though, and not the DLP chip.

Thanks Alan.

I do have sync issues with my 2005 unit :-/ Disabling the noise reduction can help, and for DVDs I can adjust the audio delay on my Oppo. Sometimes ITMS/QT over DVI-HDMI gets out of sync. I'd love to upgrade to a [bigger!] current model with HDMI1.3+ and upgrade to Oppo's forthcoming Blueray player to avoid it, but I can't justify that expense.

onn,

Home Theater magazine did a shootout this past February or March that included rear projection, lcd and plasmas from different companies. The LED Samsung rear projection set came in dead last. The two biggest problems they listed were very bright picture in the center and then more dim towards outside, very high contrast ratio. The one and two position in the shootout was the 720p Pioneer Kuro and the 1080p Panasonic plasma respectively. The Pioneer was the only 720p set and it beat every other 1080p set in the shootout because of its contrast ratio( the panel of judges didn't know what brand or model each tv was in the shootout). In the middle was (and not very close to one and two positions) Sony SXRD, Sharp lcd, JVC lcd and the Mitsubishi diamond rear projection. If you can afford the Pioneer Kuro then buy it and don't look back. It doesn't have much competition except for the Panasonic 1080p plasma right now. I tryed the Samsung lnt5265 against the Pioneer pdp5080hd and immediately knew that the Samsung was going back store as soon as possible. The Samsung 5265 was the only lcd near the price of the Pioneer in its size at the time. The difference in contrast ratio is very clear. I haven't seen the local dimming lcd's vs. plasma but I think that it is still kind of expensive and plasma still is probably a little bit better in contrast ratio and viewing angle. I say go with the Pioneer, I am very happy with mine. People are blown away at the high def picture from the Pioneer when they come over.

- Nick

+1 for the Kuro

Father-in-law has it, and I only wish I had that kind of scratch. It's beautiful

Well I pulled the plug and bought a Samsung HL61A750 for $1900. If I don't like it I will go with the Pioneer at a later date. Thanks to everyone for your opinions.
Mel N.

The pdp5080hd can easily be found for $2200 to $2500.

- Nick

Interesting, Nick. I agree that plasma is a superior technology and produces a crisper, more punchy picture.

But from a value perspective, I think it's too close a call to totally knock out DLPs just yet.

Congrats on the decision Onn. I bet once you get it home and calibrate it, you won't look back. I bet the differences are too insignificant to worry about, especially if you don't have a side by side comparison that highlights any supposed shortcomings it may have.

For me the choice was between quite a few options. The plasma (PRO-151FD) and the Samsung DLP LED (HL61A750). If I choose the plasma, the model I was looking at I could buy 3 Samsungs for the price. With plasma there is also the burn-in that might occur (even though burn-in is highly unlikey). Since, compared to my 27" crt both of these options would be better, would I really notice that much of a difference? I went with the choice that made sense to me at the moment, the Pioneer will still be waiting for me if I decide the Samsung doesn't tickle my Axioms. It's all about choice, what one is willing to accept and not accept. I have noticed that others go by their priorities in regards to choosing their sets and me as an individual try to see something in others experiences that jive with my own to help make up that decision I hope that my decision making processes aren't totally out of wack. Only time will tell.
Sorry to ramble.
Mel N.
Does any of this make sense?

Hi onn,

I think you'll be happy with the Samsung DLP. As to the Home Theater magazine reviews, I mostly disagree with their rankings. I don't know who the reviewer(s) is or are, but in the past some of their reviews have been, uhm, rather casual, not well controlled.

For example, I've always been underwhelmed by the Pioneer plasma sets--greatly overpriced and I've found picture quality to be inferior to the Panasonic plasma panels or the Sony Bravia LCD panels, the latest generation of which are really quite excellent.

As to Samsung DLP problems, my 4-year-old DLP has inaudible fan noise and I've had no problems with lip sync. As a group, rear-projection DLP sets do have more reliability troubles long-term, but that's only if you count bulb replacement as a "problem."

I honestly believe the over-the-top praise for the Pioneer plasmas is because the reviewers know the price of the set while they are making judgments. In other words, the brand names and prices are not concealed, and the same bias that exists in uncontrolled speaker evaluation, where the brand, price and size of the speakers are visible, also biases video reviewers at magazines and web sites.

The only Pioneer plasma that I was greatly impressed with was when HD first went on the air, and a $30,000 Pioneer plasma on loan was calibrated by a former colleague of mine at etown, Kevin Miller. He is an ISF calibrator and reviews displays occasionally for Cnet. The occasion was a Super Bowl party and most of the guests were professional AV reviewers, editors and journalists.

Displays have greatly improved. Four years ago, I would always recommend DLP over LCD panels, which had lots of visible problems, as well as plamsas, unless the person had an unlimited budget, as plasmas then were a lot more expensive than DLP in an equivalent screen size. Costs have come down dramatically, and many of LCD's early problems (grayish black levels, image smearing with fast lateral motion, etc.) have been largely overcome.

Anyway, enjoy your Samsung and give us an update after a while. As you may be aware, the DLP sets deliver their best picture on the "Cinema" setting, suitable for dimly lit or dark rooms. That also goes for the LCD and plasma displays.

Regards,

Thanks for the response Alan. I have gone to the avs forum as per Fredk's input and found some settings I will use for my set-up when my TV arrives next week.
Thanks
Mel N.

Hey Peter, I was wondering what settings you are using for your Samsung. When I get a chance I will post mine.
Mel N.

Cool. We own the same TV. Good choice.

I'm not at home in front of the set, so I don't remember exactly what they are. I spent several hours tinkering. Didn't use any special calibration tools, just spent time looking at programming with people and nature scenes. My final settings ended up being based on the 'Dynamic' profile. I took the brightness *way* down and the color intensity and contrast down just a bit. I want to say that the brightness default was at like 90 and I took it down to around 60. I think I put the colors and contrast back around 50. I tweaked the sharpness as well. Just don't quote me on those numbers.

The result is a picture in which all of the colors look very natural to me and my wife in all lighting conditions. Nice and colorful, without being overblown. Deep blacks but not so dark that I can't see details on bright and sunny days (my den has windows).

However, when watching a movie at night in a dim room, I do actually like the default 'Movie' mode. I may have tweaked it's brightness down just a few points, but not much at all.

As is common with all HDTV's and previously mentioned, the default settings are based more on sales in a store than at home. The default 'Dynamic' setting's colors were so bright and overboosted that it gave me a headache.

I've had my LED Samsung HL-T6189S for a year now and must say that I am completely satisfied with it - everything run in via HDMI the picture quality is just awesome

So Peter here are my settings for now
Mode - Movie
Contrast - 100
Brightness - 47
Sharpness - 10
Color - 50
Tint - G49/R51
Black Adjust - Medium
Dynamic Contrast - Low
LED Control - Auto
Gamma - -3
White Balance and Flesh Tone - 0
Edge Enhancement and xvYCC - On
Color Tone - Warm 2
I'll keep experimenting over time to see if I can tweek it a little more. Sorry for the long post everyone
Mel N.