Grey Hawk is not for Joe Six Pack - AVS Forum
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post #1 of 15 Old 08-14-2001, 09:49 PM - Thread Starter
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Hi
I installed 2 New Yamaha DX-1 DLP's last week
Both Installs had Grey Hawks as per Stewart's
recommendation.Both projectors were calibrated
and Both clients objected to the brightness of the
image.This projector would look better if mated
with a VideoMatt 150.I would suggest Stewart reevaluate
its position on recommending the GreyHawk with this projector.
Cheers Ray

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post #2 of 15 Old 08-15-2001, 05:45 AM
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Ray, are you saying the clients thought it was too bright???

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post #3 of 15 Old 08-15-2001, 02:40 PM - Thread Starter
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Hi
No too dim,Yamaha backed off on there advertised 1000 ASI
Lumen spec.This projector needs a higher gain screen
when the size is over 100" diag.If you had a totaly
black room a GrayHawk would be ok up to 100" diag.
I believe what you gain in contrast with the GrayHawk
is a Wash(pun intended) when compared to what you loose in
brightness
Cheers Ray

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post #4 of 15 Old 08-16-2001, 10:15 AM
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Ray,

What's with the title of your post? The Yamaha doesn't strike me as a "Joe Six Pack" kind of projector. Where's the LT150? http://www.avsforum.com/ubb/biggrin.gif

Anyways, what screen size and aspect ratio were you using in your installs? How far below their 1000 lumen spec do you think the Yamaha is? I imagine you should probably call Stewart and let them know, because they probably are making their recommendations on the specs they have from Yamaha. Hopefully you can work out a fabric swap for a higher gain surface, Stewart is pretty good for stuff like that.

BTW, I saw the DX-1 at CES this year on a protoype Greyhawk and a similarly sized screen (100"). It did not look dim to me, how large did you go with it?

Regards,

Kam Fung

[This message has been edited by KFung (edited 08-16-2001).]
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post #5 of 15 Old 08-16-2001, 04:50 PM
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Grayhawk is definitely not for every digital projector. Yes it does help dramatically with the black levels, but it is also only a .85 gain. If you don't have enough brightness, your image will lack punch. I noticed this when I put the Seleco HT200DM on a overly large grayhawk. The colors and black levels were fabulous, but there was no "umph" to the picture. If one does decide on the grayhawk, make sure your are not going to large on the screen for your particualar projector.

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post #6 of 15 Old 08-16-2001, 08:09 PM - Thread Starter
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Hi
All
Jason,You echo my thoughts exactly.The GrayHawk is not
a good choice for many digital projectors.I think High
Lumen DILA's would be great but DLP's I would think twice about.Kam,If you remember The CES presentation of the
DX-1 was in a pitch black room,showing Animation
What I meant by Joe Six Pack is limited knowledge
regarding installation and calibration,One quote from
one of the clients was why doesn't this look as bright as my
27" TV ? He had a 136" diag GrayHawk with ambient light
spilling in too the room.http://www.avsforum.com/ubb/smile.gifI highly recommend a max of 110"
diag and a 1.5 gain screen with this projector.I hope Don
reads this post http://www.avsforum.com/ubb/smile.gif
Cheers Ray

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post #7 of 15 Old 08-17-2001, 09:16 PM
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In some ways I agree with both of you, but I think I will modify your statements. Really is should not be "the Greyhawk is not suitable for every/many digital projectors", more accurately is could be stated that "the Greyhawk is not suitable for all situations with any digital projector".

I think we all know that screen don't "care" which projector is put on it. If I push a G15 to >12' wide the Greyhawk is definitely not going to give a bright image and should not be used. On the other hand a 10' wide Greyhawk with a G15 will give an excellent image in a light controlled environment (~17 ft-lamberts). On an 8' wide screen this combination would give a pretty acceptable image even in low to moderate ambient light (~30 ft-lamberts).

Shooting 1000 lumens onto a 136" Greyhawk screen *is* quite doable *if* the projector meets its specs and *if* you have reasonable light control. I often wonder where manufacturers come up with their brightness specs, I've seen projectors that are lucky to make half their brightness specs when measured.

If your client was expecting an image as bright as a 27" direct view on a 136" screen with ambient light, he's obviously got his sights set too high. That would require a projector over 2000 lumens, preferable 3000+. Those are not cheap! I like to remind people that we are looking at home *theatre*, the objective is to get an image like what we see in the theatre, that usually gives them a better point of comparison than a direct view television. Tell you client to think of it as a theatre projector made smaller to fit in the home, if he compares his front projection system to a direct view TV he will inevitably be disappointed.

I should say that the Greyhawk is inherently better suited for digital projectors where black level is still an issue (except when you get in to the very high end D-Cinema projectors). It will give you better blacks, better contrast, better colour saturation, and better ambient light rejection. The Greyhawk is the proper choice in situations with ambient light because it will maintain black level much better and won't wash out as easily, but anytime you have ambient light you need *a lot* more lumens no matter what gain screen you use.

If you move to a higher gain, non-grey screen you give up these benefits. That is the trade-off if you want to push the screen size to the limit of what the projector is capable of. On CRT's it is, of course, not the same because they have ample black level but not enough brightness.

Of course, if you made clear to the person at Stewart that this was a 1000 lumen projector shooting onto a 136" screen with ambient light and they still recommended you a Greyhawk I think that was probably a mistake. OTOH, in a light controlled room that would probably provide you with an optimum image within the range of the SMPTE brightness spec.

BTW, at CES there were two demos with the DX-1. One that you could walk into that was showing Toy Story 2, that was not a light controlled room, though, with light spilling in through the doors. Nevertheless, the projector looked decent. The other demo was in a light controlled theatre and they were showing U571, MI2, and some live concert footage. All were very impressive and not at all too dim even on a screen size comparable to what you had. Too bad the Sharp looks like it will beat the DX-1 in almost every way. What a difference 8 months makes! http://www.avsforum.com/ubb/smile.gif

1.5 gain on a 110" screen is a bit of overkill IMHO. The projector isn't that far below its specs is it?

Regards,

Kam Fung

[This message has been edited by KFung (edited 08-17-2001).]
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post #8 of 15 Old 08-18-2001, 06:45 AM
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Aren't the new GrayHawks .95 Gain??

I remember reading they changed the reflectivity because most Digital Projectors do not output the rated Lumens.

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post #9 of 15 Old 08-18-2001, 07:19 AM
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I saw two Yamaha projectors in adjacent rooms at CES, one with a Grayhawk, one without. The one with had notably better contrast and black level but on recollection, may also have been a bit dark, at least on the MI2 demo.

I just installed my own Grayhawk with a 2500 lumen Sanyo LCD. The improvement to black level and contrast is really amazing, but I could see how this screen also needs a fair amount of light output, which is lacking in the current generation of DLP.

BTW, I'd be surprised if this screen is 0.95 gain--it eats enough light to convince me it is 0.85. Maybe we should suggest to Stewart they make a 0.95 gain for these DLP projectors. That should still provide some contrast/black level enhancement while "eating" less light.

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post #10 of 15 Old 08-18-2001, 12:05 PM
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My understanding was .95 for the latest (i.e. not early) Grayhawk's, and .85 for the microperf Grayhawk's.

Kam's suggestion of using foot lamberts as the decisive characteristic of the installation seems to me a good one. It would be great to divise ratings for each screen size w/ the Grayhawk.

For instance, a 7' Grayhawk with the LT150 might be swell, while 8' and greater is too much (no experience behind these figures, just imagined examples).

Kelly


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post #11 of 15 Old 08-18-2001, 12:11 PM
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The regular Grayhawk is a .85 gain, although it actually tests out a bit higher, around .90 gain. Stewart rates there screens conservatively...another plus. The microperf has a slight increase in gain, .95, to help counter the 10% drop in brightness caused by the holes.

Thanks!

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post #12 of 15 Old 08-18-2001, 02:58 PM
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OK, I got it now.

I looked back at older threads from Don Stewart.

He explained that the vanilla GrayHawk is .95 Gain (increased from the original .85 gain), while the THX Microperf Screen is (quoting Mr. Stewart):
------------------
For THX Micro Perforated sound screens we increased the translucent reflective optical coating to a gain of almost one. Then we perforate the screen with approximately 30,000 holes per square foot and leave about 10 percent of the screen surface on the floor. The net reflectivity is .9
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post #13 of 15 Old 08-20-2001, 10:41 AM
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Wow! If this screen I have here is 0.95 gain, that earlier 0.85 gain screen must have been one dark momma!

Whatever, it is a fantastic screen. I particularly like the vellum covered wider frame (both options) I ordered. There is simply no light spill whatsoever. It is so absorbent it actually makes fitting the picture to the screen a little tricky.

Dan

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post #14 of 15 Old 08-20-2001, 04:20 PM
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Kelly,

Yes, brightness as ft-Lamberts or candelas/m^2 really should be the measurement of choice. Unfortunately, few people have the test equipment necessary to test accurately ($$). What we really need is a test centre that would test new projectors and determine their actual values, not the marketing specs. Of course the manufacturers would never let the organization borrow the projectors!

Regards,

Kam Fung
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post #15 of 15 Old 08-21-2001, 07:08 PM
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Life becomes a breeze when you can get good results with screen gains of(2-3).
http://www.avsforum.com/ubb/smile.gif

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