[Yahoo]

I'm on the verge of buying a high-power 2.8 gain screen for the LT150...can anyone who has gone from a low to a high power screen on their LT150 please post your experience here...? It seems to make sense rainbow effect would be amplified if there were any to begin with...but if there was none and now after getting high-power you start seeing them...that would be food-for-consideration. http://www.avsforum.com/ubb/smile.gif


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[Darian]

Please read this post that was a back and forth between a forum member and myself.


Darian's New Toy


cai:

1.- Did you get the NEC-LT 150 DLP?

2.- How is the screen door in this projector, how far away from the screen do you have to sit for this effect to disappear?

3.- How strongly would you recommend a DLP, LCD, or DILA, in lieu of a CRT?

4.- Have you ever seen a DILA projector that has beeen properly calibrated, what are your impressions versus the DLP?

5.- Do you notice the rainbow effect, and when does this happen?

6.- Is it very noisy, or how noisy is it? Like a computer?

7.- Is there a light leakage issue, can it be plugged?

8.- Does this projector get very hot does it need a special housing?


1. Uhh huh.

2. You have to get pretty close to the screen to see the grid. Talking like 2 or 3 feet on a 60 inch image. Much smaller than LCDs and closer together.

3. DLP is great if you are going to be viewing things that don't fill up the whole panel. There is no threat of burn in. The bulbs are not real long lasting. This thing wieghs in at under 4 pounds and fits in one paw. Forget convergence, multiple aspect ratio setups, blah blah blah! Point, focus, picture.

4. Only seen a DILA at CES 2000 in JVC booth. Needless to say, it's advanced considerably since then. Cost makes it most prohibitive. That's when you forget about the noise, the heat, the funky lenses, the scaler, the hushbox, etc.

5. yup. Primates' eyes naturally track back and forth and vertically. This helps us to judge distance and depth (one of those hunting things, ya know?). Violently shaking your head about will exacerbate the problem. All you need to do is set the screen size so that it dominates most of your field of view.

6. Not too noisy, but we will be doing some things to make it quieter.

7. Si y oui. Construction paper and matte knife cured the problem in less than five minutes. You could take this a step further by specifically cutting out specific croppings.

8. Very is a relative term. I can pick it up with the thing on and not burn myself. How hot are we talking about here?


***************


Rainbows are based on your eyes moving. If you could force yourself to hold your eyes still then the rianbows won't be seen.

 

[srauly]

cai's answer to #5 doesn't make sense to me. I would think that if you used a very big screen so as to fill your field of view, you would end up moving your head to follow the action more than if you had a smaller screen which allowed you to see all of the action without moving your head. What do you think?


Scott

 

[Darian]

Actually Cai had posed the questions and asked that I not reply with Yes or No answers.


As for the dominating the field of view. If you are sitting behind the projector it is usually a good distance not to see the screen door. Add a few more feet and your vield of view should be dominated by the screen without too much chasing going on.


Years ago when True Lies first came out I went to the biggest theater we have out here in the DC area. I got the showing a little lats and had to sit in the front row of a gigantic theater. This theater is so big it has 2 balcony seating sections. While watching this movie not only was my neck ent all the way ack most of the time... but i had to chase objects around the screen. Moving my eyes was not enought and I had to move my head. If this had been a single chip DLP all I would have seen is rainbows.


What I am trying to point out is this.


RAINBOWS HAVE ALMOST NOTHING TO DO WITH SCREEN GAIN! It is all about how much your eyes are moving vs the refresh / spinning rate of the color wheel.

 

[hsitz]

I don't have an LT150, but I do have a DLP. I also disagree with the people who say that high-gain exacerbates the rainbow. For a while I used a white sheet (gain of well less than 1, I would guess) as my temporary screen. Then I upgraded to a Dalite High Power with 2.8 gain. I was watching carefully for differences in rainbow after the switch and I couldn't tell any difference at all. -- Herb



[This message has been edited by hsitz (edited 07-13-2001).]

 

[srauly]

OK, I think we're in agreement. Just to clarify, you want to make the screen as small as you can tolerate (or, similarly, sit back as far as you can tolerate), so that you don't have to move your head at all. Correct?


Scott

 

[Dave E in TX]

I have a ceiling mounted LT150 projecting a 80x60 image on a 1.5gain Dalite screen. I sit about 15' back. I have only very rarely seen rainbows. Mostly when I dart my eyes back and forth on purpose, or I turn to look at something other than the screen.


For me, its not much of a distraction. I realized last night that I don't recall ever seeing them on regular TV (directv through svideo). This is odd, perhaps next time I see them I'll rewatch the same scene via svideo and see if they're still apparent.


I also just got (last night) a DVDO (the original V1 "plus" edition)...which are available cheap on ebay (I got mine for <$200). This thing really helps the svideo picture a lot. Its not quite as good as the JVC progressive scan DVD player I have, but definitely improves any svideo source.


Anyways, I plan on upgrading to a highpower screen. I will post my impressions once I get it...


-Dave

 

[Yahoo]

Thanks Darian and hsitz...that's what I thought too from a theoretical standpoint but I just wanted to be sure....


Before I forget...I have used the LT150 for 4+ months on my Matt White with no noticeable rainbows. A few days ago I read the posts on turning off the WHITE SEGMENT and found that all that time I had the WHITE SEGMENT checked. Nothing wrong with that as I enjoyed the pictures immensely. However, I decided to give it a shot and UNCHECKED the WHITE SEGMENT and...well...now I really need the HI-POWER screen because the brightness is noticeably reduced. In fact, reduced to a point where I cannot enjoy the pictures as much as before if I had ambient lighting. I have to watch it pretty much in total darkness. To be fair, I did notice that the color depth/accuracy improved somewhat after turning off the WHITE SEGMENT but I really doubt the average non-critic would have observed this kind of improvement. I guess this is where the HI-POWER comes in and compensates for the reduced brightness.


Ok here goes my order for the high-power... http://www.avsforum.com/ubb/smile.gif


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Editor of the Skyworth FAQ page at:
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[This message has been edited by Yahoo (edited 07-13-2001).]

 

[srauly]

Interesting discovery Yahoo. Grant, can you comment on this? I'm wondering what kind of results leaving the WHITE SEGMENT turned on and using a Grayhawk screen would produce. Anyone able to test this or comment further as to why WHITE SEGMENT should be turned off?


Scott

 

[Grant Smyth]

I am in complete agreement with Darian's comments and others who don't feel that the gain of the screen has much to do with "rainbow". I feel that eye movement and processing power or lack of it has more effect on rainbow. The reason for this opinion - questioning those who do see rainbow and experimenting with what they see under different conditions. I also think that leaving the "white segment" on will make rainbow more of a potential problem!


For me, the "white segment" on caused some problems that forced me to pause when considering whether or not to purchase the LT150. I loved the picture, but on some DVDs (not all) I was seeing "crawlies" or video noise (looks like a swarm of insects in sky scenes). When the "white segment" was turned off this went away - I immediately purchased the LT150 - it's not perfect, but for me it's pretty close!


I didn't fully realize how good the Hipower was with the LT150 until I tested other screen material against it - no contest! I became a "real" believer after that!


If I had a grey screen (I have a homemade one if that counts) I would definitely try the LT150 with the "white segment" on and I would adjust other settings as well! I would also compare it with the Hipower just to see if I were missing anything!


Cheers,


Grant

 

[Yahoo]

Ok this will come as a shock to some of you, but I did see RAINBOW tonight on my CAST AWAY rental.


The RAINBOW was not noticeable in the movie but it was very evident in the "Making of CAST AWAY" feature on disc #2. You can easily see this by fast-forwarding to the section that begins FIJI MARCH 1999 where Tom Hanks is standing in front of a bunch of palm trees. The RAINBOW is evident on the tree leaves. I also noticed that the RAINBOW occurs even more noticeably during PAUSE and FAST-FORWARD/REWIND on the same footage...I wonder why. Perhaps the video source materials recorded at certain speeds/resolutions exacerbate this effect? It is a relieve to not see the effect in the movie.


Just to be sure it is not limited to my new RP91 I tried the same disc on the Skyworth and it was even more pronounced (by about 10% more). To make sure this is a phenomenon that is not DVD Player dependent in any way I will be plugging in the JVC 723 back tonight for comparison, as I ponder on why this RAINBOW EFFECT was not evident in the last 4 months and I do watch every "bonus" material that has graced the LT150 screen. (No I could not have missed it in the last 4 months if you think it is because I started looking for it just recently, I assure you.) Could it be the combination of adjustments I'd made recently on the LT150...hard to say since I have also changed DVD players and started playing with Video Essentials and the WHITE SEGMENT setting...but I will share with you my findings after the JVC test.


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[This message has been edited by Yahoo (edited 07-14-2001).]

 

[tlastrange]

I too think rainbows on the LT150 are much more visible on video based material. I was watching Sarah McLachlan's Mirrorball concert and I was seeing them more frequently. Of course it could have been the fact that my eyes are darting all over the place looking at the screen samples still taped to the wall.


One of these days, I'll actually sit down and watch a movie rather than trying to analyze every detail of the picture, dvd playback, screen, etc. Nahhhhh http://www.avsforum.com/ubb/smile.gif


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Tom L.
my-soontobe-home-theater


[This message has been edited by tlastrange (edited 07-14-2001).]

 

[nelson]

Is the appearance of rainbows also related to the amount that the projected image is enlarged?


For example, if the projector is placed to display a 4 feet wide image and then moved to display an 8 feet wide image (without making any alterations to the zoom setting if the projector has a zoom), the pixel size must be effectively doubled. Does this result in little rainbows becoming bigger rainbows, or unnoticed rainbows suddenly becoming apparent? Or is their visibility independent of image enlargement?


I would test this myself, but I am still a mere lurker here, my money is still in the bank at present. However, my home extension is nearing completion at last, so before too long I should be able to join you lucky guys! (I'm still swayed towards the LT150 from all the comments that have appeared since Grant's initial reviews).


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regards

Nelson

 

[Yahoo]

The appearance of rainbows does NOT seem to have anything to do with the screen size. I have the same 100" screen the whole time I owned LT150 and this was not noticeable until last night. Of course, if you use the same screen at 100" and then go back to let's say 60" you will see the same rainbows just smaller in size relative to the proportion of the screen. http://www.avsforum.com/ubb/smile.gif


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[This message has been edited by Yahoo (edited 07-14-2001).]

 

[nelson]

Sorry if my question wasn't explained too clearly. I guess what I was trying to say was, is there are a certain level of image enlargement that would reveal rainbows more obviously, i.e. steer clear of screens above a specific size, or alternatively keep to a screen of less than a specific size and the rainbows won't be noticed.


But I take it that you are saying that if a rainbow is noticeable in any scene, it will always be noticeable but always in proportion to the displayed image size.


I was just curious if the rainbow effect became exagerated the greater the level of image enlargement, (i.e. not proportional).


I don't think I have explained myself any better than the first time. I'll shutup!


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regards

Nelson

 

[Yahoo]

Rather than getting into theories, let's just say screen resolution/size doesn't matter for what you buy the LT150 for (i.e. I don't think you will use the LT150 to project on a 32" screen). The rainbow will be visible if you are "sensitive" to it. I guess I'm not sensitive to it but I do "see it" more on the Infocus LP350 than on the NEC LT150, and more on the video based source than film-source (so far only on the LP350). You really need to try it out for yourself. http://www.avsforum.com/ubb/smile.gif


I do want to add that if your screen is larger than your field of view you will probably notice it more simply because you have to dart your eyes constantly across larger surfaces/distances at a relatively high speed, as others have suggested.


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[This message has been edited by Yahoo (edited 07-14-2001).]

 

[Darian]

Not to be a dick...


But do you guys know the differance between Rainbows and Morie? Morie is often visable in bad deinterlacing with crummy sources. Especialy if you have sharp trasnition like lines.


If you think the tree has rainbows???I think you may be looking at Morie. to test it. walk up to the screen to where you see the screen door. now pick a group of pixels and focus your attention there. DO NOT MOVE YOUR HEAD OR YOUR EYES! if you see a image that sort of pulses in the fine detail and has a bunch of colors... you are seeing MORIE not the rainbow effect.


Check it out and get back to us.


[This message has been edited by Darian (edited 07-15-2001).]

 

[jimbob]

Just a quick query for all the new and potentially new hi-power da-lite purchasers:

Where are you buying the screens from? I guess I'd be looking for a 60x80 screen, but I don't see a price for a hi-power version on any web-page..... and price is important for me - especially since it looks like a lt150+screen might just go under the 3k barrier - or am I dreaming? http://www.avsforum.com/ubb/smile.gif


Thanks,


Chris


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[This message has been edited by jimbob (edited 07-15-2001).]

 

[Steve Dodds]

I am rainbow sensitive, but haven't noticed any increase in rainbow with my High Power screen. In previous projectors, it seemed much more apparent with those with hot white problems, ie NEC LT100, Proxima DX3.


My problem with the High Power is that the added gain raises black levels. That's why I have a matte white 16:9 beneath my 4:3 High Power.


For DVDs, I simply raise the Da Lite and use the matte screen. For less critical watching I use the High Power.


Try www.cousinsvideo.com for good prices. Mine cost $270 including shipping there.


Steve


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Steve's Stuff


[This message has been edited by Steve Dodds (edited 07-15-2001).]

 

[Yahoo]

Speaking of high-power raising the black level...can it not be readjusted on the video calibration to compensate for it?


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