DIY Scrren versus GrayHawk sample - AVS Forum
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Old 06-22-2001, 11:25 AM - Thread Starter
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Hi,

I just thought I post my initial testing with the large GrayHawk sample that I received yesterday. First and foremost, I'd like to thank Stewart for sending the sample.

My wall is painted in a flat Ralph Lauren Dover Cliffs gray paint. My DLP is an Infocus 340. Ok, I taped the sample dead center of my wall (a.k.a. my screen http://www.avsforum.com/ubb/smile.gif ) and just did a sampling of my newest DVD "The Dream IS Alive". I have a fair amount of ambient, that is why I wanted to evaluate the GrayHawk. The material is very heavy and has some stretch to it, I can see why it needs to be tensioned.

Anyway, I did not notice that big a difference. The sky looked bluer (as did most of the image on the sample) which gave it a slight more punchy look, but in dark scenes, it didn't notice any more shadow detail. By this time, it was totally dark in my room so ambient was no longer an issue.

Thanks again to Stewart for the sample.

Jay

[This message has been edited by Jay C (edited 06-25-2001).]
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Old 06-22-2001, 05:50 PM
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I just finished doing a similar test. I have a friend who is buying a Grayhawk, he brought over the sample Stewart sent him.

My screen has already been painted "veil" grey, which is a moderately dark gray. My screen is painter's canvas. I also compared it to a sample of the original white canvas material taped on the screen and a sample of gray painted canvas with pearlescent paint on top.

I have an uncalibrated G1000, and my screen is 114" wide.

My grey is a good "two shades" darker than the GrayHawk. They GrayHawk is actually a gray rubber material with silver/pearlescent-like paint "splattered" lightly on top. I would say that it has 30% splatter coverage, with 70% grey showing.

My observations are as follows:

Unpainted white canvas
Overall brightness: plenty bright
Saturation: lighter colors (yellows especially), are very vibrant and saturated. Darker colors looked less saturated.
Blacks: are fairly washed out.
Contrast: Lacks "depth".
Hotspotting: none

GrayHawk
Brightness: not as bright as the white, but brighter than my gray.
Saturation: Lighter colors were more vibrant than my grey still lacking saturation compared to white. Darker colors (especially dark blue and red) had more saturation.
Blacks: The biggest surprise was the GrayHawk's blacks were nearly identical to the white screen. The more we looked at it the more we couldn't believe our eyes. Using my "highly calibrated" eye I would say that the GrayHawk's blacks were only about a "half shade" darker than the white. Very unexpected.
Contrast: better than white, but not dramatically. Also lacking in "depth".
Hotspotting: none

Gray painted canvas("veil" from glidden from home depo)
Brightness: fairly dark overall, once my eyes adjust, it becomes very tolerable.
Saturation: light colors (especially yellows) look "dingy" and unsaturated (example: walls of Bruce Willis' apartment in Fifth Element). Dark colors look very saturated.
Blacks: Amazing!! Jet black, like looking into a black hole.
Contrast: Once your eyes adjust to the dim picture, the contrast looks excellent. When watching bright HDTV scenes, I feel like I could get out of my couch and walk into the movie.
Hotspotting: none

Canvas painted "veil" gray then painted with pearlescent FX paint
Brightness: Somewhere between GrayHawk and veil.
Saturation: same as veil
Blacks: blacker than GrayHawk, but not as black as "Veil"
Contrast: VERY good. Dark blacks, and striking highlights.
Hotspotting: severe hotspotting problems. To the point of being unusable.

Conclusions
Given all of the options, I would say that I prefer my current setup, Veil grey painted on canvas - no pearlescent. (actually I premixed a bunch of perlescent into my paint, but they gray overwhelmed the pearlescent eliminated any positive effects). It will be interesting to see how the overall brightness improves with my Panamorph when (if?) it shows up.

Advice to Stewart: make your base gray darker, you have an impressive coating, but the gray is too light (for me).

Jeremy

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[This message has been edited by JeremyNeish (edited 06-22-2001).]

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Old 06-22-2001, 07:23 PM
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Jeremy and Jay,

I saw the Greyhawk demo at the Stewart booth during Infocomm and I was quite impressed with the performance, perhaps I can provide some explanations for the results you are seeing.

Jay C,

The Greyhawk really starts to stand out from a plain grey screen when you have ambient light. If you room is very dark and the walls do not reflect a lot of light, you probably won't notice a tremendous improvement. In the Stewart demo they also had a floor lamp that you could turn on and compare the performance to their 1.3 gain material. Once you add ambient light, the optical coating and the grey backing provide much better performance than a conventional screen or a regular grey screen. OTOH, if your are primarily watching in a low-ambient conditions your painted wall may provide you with the performance you need at a more economical price.

Jeremy,

In your case I would strongly recommend you calibrate your D-ILA, the G1000 is really kind of pushing it on a that size of a screen (I think you must be getting less than 12 ft-lamberts on such a screen and shooting onto a conventional grey screen may give you too little brightness for a good picture). I am not that surprised that the Greyhawk has a black level very similar to your matt white canvas, the Greyhawk has a gain of almost 1.0 so it should look very much like a matt screen. Where you will see a difference is in ambient light performance over that matt white and if you room is not darkly coloured you should also see better contrast performance in scenes with mixed light and dark. If you are seeing that the black is 1/2 shade darker, that is already quite an impressive increase in contrast if you are not sacrificing your whites to accomplish it.

If you eyes have to "adjust" to your current grey screen you definitely need more brightness, calibrating your D-ILA will get you much (much) better blacks and you won't need such a dark grey to get acceptable blacks and you won't need to sacrifice as much brightness. The G1000's especially benefit greatly from calibration.

I think in the future Stewart will offer a line of Greyhawk screens with different shades of grey and gains, however I think they're sticking to with just one shade and gain until consumers get more experience with it so that they won't make the wrong decisions.

Regards,

Kam Fung
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Old 06-22-2001, 08:55 PM
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Say Kam,
This is good news for people with near blackout rooms(or nearly everyone else in the evening)they can just dispense with grey screens and their loss in gain,save themselves $4000.CDN dollars(10ft)and get a PJ for free.
http://www.avsforum.com/ubb/smile.gifsorry Don

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Old 06-25-2001, 12:20 PM
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Unless your room completely minimizes internal reflection (black velvet walls, ceilings, etc.) you will still derive non-trivial benefits from a painted grey screen or a Greyhawk. The grey screen absorbs light from secondary reflections off of walls and other surfaces, increasing actual contrast in projected images (and ANSI contrast as well). The Greyhawk improves on this performance by reducing the loss in brightness and reducing the effect of reflected light from higher angles.

If you have the lumens to spare a grey screen is probably a more economical way of increasing contrast than totally blacking out your room (although that will give the best results).

Regards,

Kam Fung
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Old 06-25-2001, 01:06 PM - Thread Starter
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Quote:
Originally posted by KFung:
Jay C,

The GrayHawk really starts to stand out from a plain grey screen when you have ambient light. If you room is very dark and the walls do not reflect a lot of light, you probably won't notice a tremendous improvement. In the Stewart demo they also had a floor lamp that you could turn on and compare the performance to their 1.3 gain material. Once you add ambient light, the optical coating and the grey backing provide much better performance than a conventional screen or a regular grey screen. OTOH, if your are primarily watching in a low-ambient conditions your painted wall may provide you with the performance you need at a more economical price.

Regards,

Kam Fung[/b]
Hi Kam,

I have a lot of ambient light, and no real acceptable way to control it (WAF). I was able to do some testing with some ambient (sun set) and the difference was not obvious to myself nor my wife. However, I do admit that I need to do further testing before I write off GrayHawk. I really do need a screen that can reject ambient light to make daytime viewing acceptable. However, my initial reaction/results were not impressive enough for me to invest....yet.

I will move the sample and do some morning tests as well.

Thanks for your feedback,
Jay
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Old 06-25-2001, 07:20 PM
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Don Stewart has a demo with one half Greyhawk, one half matte screen.

If you get a chance to see it, do. The difference is stunning.

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