DLP rainbows

[Jim McC]

Why do rainbows affect some people and not others? Is there an optometrist out there?

 

[TT9]

I've noticed a definite identifiable relationship between buying power and susceptibility.

. . . 'The HT300 gave me headaches and I saw rainbows so I bought a Z1'. . .

 

[docfeelgood]

TT9.... I can see the rainbow effect very easily. In fact on one occassion it was so bad that I felt sick. After I had finished the demo I could still see the rainbow artifacts when I blinked !

This was from a PJ I wanted to buy... and had the money to buy... I was gutted.

The problem exists for many people who are sensitive to it.

It is misleading to imply otherwise.

I would be very dissapointed if I spent 3k on a nice DLP only to get it home and not be able to relax and watch it.

Then there's friends and family. How do you know if they are sensitive to this. Not much cop if no-one else will watch a movie with you because 'it makes them feel sick and dizzy'.

Firstly... make sure you demo a DLP in proper conditions.
Secondly.. are you likely to be using this alone? ... if not then take along some of the people who will be watching to the demo.

cheers

Doc

 

[uczmeg]

I agree with Doc, demoing DLP is a must.

Not all DLPs are equal, so try and demo the one you are most interested in. Or if you really want to be sure demo something cheap like the Infocus X1 with it's slower colour wheel. If you are OK with that then you are OK with anything.

Once I'd seen that the wife was fine with DLP and how much nicer DLP was over LCD I thought, sod the friends. 95% of the watching is just the two of us. I'll take the chance on the rest of them!

Luckily the dozen viewers so far have been fine.

Cheers
Marc

 

[SanPedro]

Cheaper DLPs are more noticeable. I've seen the Sim Domino 20 and didn't see a thing untoward. Some cheaper machines have been quite noticeable from my experience.

I'd guess that within 18 months - 2 years (maybe sooner), as the faster colour wheels filter down to the cheaper models then rainbow will be less of an issue to most peple.

CL

 

[gizlaroc]

Although I dont suffer too badly from rainbows, I do get a headache from DLP units, I find myself frowning after 45 minutes or so and it starts to really hurt after about an hour and a half.

So it would be advisable to get as long a demo as possible.

 

[Clint C]

When I first got my HT1100 both me and the misses felt nausea creeping on. After getting advice from this very forum I found that the nausea is eliminated by sitting no closer than 2x screen width. This has to be to do with not having to scan your eyes across the picture so much when sitting too close which would in itself bring on the rainbow effect... let's face it, when you want to induce the rainbow effect people suggest wiggling your eyes left and right in dark scenes with areas of "light" in. So for me and the misses sitting further back means that the picture is still large but a whole lot more enjoyable from this wonderful DLP projector.

Clint.

 

[Peter Parker]

Hi Jim,

Are you a regular poster over at avs? If so, is your room carpeted from floor to ceiling in grey carpet, and do you have black indoor/outdoor carpet on the screen wall?

Gary.

 

[G a f f e r]

everyone has different susceptibilties to dlp. Good idea for a poll?

ps, yes they do bother me, but even though noticeable, less annoying on sim2 domino20

 

[Jim McC]

To Gary, I do post on that forum, but the answer is no to your 2 questions.

 

[LV426]

I have to guess (not being trained in such matters) that it isn't exactly an optometrist question since it isn't (I think) about focus or optical sensitivity per se but more about the speed with which either your eyes or brain can detect changes in what you see.

Long before DLPs and their rainbows, long before widescreen TVs, Sony produced a 29 inch (4x3) TV with 100hz.

Walked into the local Sony Centre with my colleague. Immediately I can pick out the 100hz TV - the lack of flicker is immediately obvious to me. Whereas, he doesn't have a clue what I'm on about.

10 (?) years later and he now admits he can see the difference.

Visibility of CRT refresh rate flicker and rainbows is, I suspect caused by the same thing - can I call it 'fast eyes'? And, my sevsitivity is certainly getting worse (ie more sensitive) as I age. The evidence from my colleague, starting from a less sensitive point, is the same.

And the pojnts made by others here are well made. At worst, you see, and are nausated by, DLP rainbows almost immediately. At best you have no idea what the problem is. In between and you may find yourself becoming 'tired' or uneasy at watching - without being able to detect exactly why.

As for keeping your screen size small and/or staying far enough away from it to avoid lateral scanning to keep rainbows at bay - this is surely tending towards defeating the whole point of home cinema - to get (close to) a cinema-like experience in the home. Rare, I think, to go to the cinema and not have to laterally scan a wide picture. Might as well buy a TV?

Roll-on 3-chip DLPs at realistic prices Until then, it's LCD (with its greyish blacks) for me - no contest.

 

[Clint C]

Nigel, sitting 1.5 to 2x screen width back isn't that unusual... It's what most people recommend. I just happen to sit 2x screen width back to get over my DLP viewing problem. So from 12 foot back I look at a 6 foot wide screen... still looks big to me and much better than watching it on my tv. Oh and did I mention how nice the blacks are?

 

[LV426]

Indeed. In my case, I sized my screen according to the largest size I could fit into the space available - it is 8 feet wide or thereabouts. And I sit about 12 feet back. Too close, I think for avoiding lateral scanning.

My point was, that I wouldn't consider using a smaller screen (to circumvent the rainbow issue) as being preferable to the (admittedly) greyish blacks - but otherwise artefact-free image I get from my LCD. My next projector (given the current state of the market) will be another LCD.

Actually, I doubt even with a 6-foot screen at this distance, I'd not have a problem with DLP.