Tilted screen with floor mounted PJ? - AVS Forum
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post #1 of 6 Old 07-27-2001, 01:52 PM - Thread Starter
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Does anyone out there have a tilted screen with a floor-mounted CRT projector?

I have been experimenting with some Stewart screen samples taped to my wall. I really like the Ultramatte 150 but I find that the vertical viewing angle is much less than the Studiotek 130. In fact, when I am seated I can't see any difference in brightness between the two. But if I stand the difference is obvious. So I tried taping the samples to a board and tilted the board. I found that the board needed to be tilted 10 degrees to maximize the brightness. My eyeline is about 3 degrees below the center of the screen.

I guess that tilting the screen will also have the bonus of reducing keystone but are there other factors I should be considering? Would it be visually disturbing to watch a screen that is tilted towards you?
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post #2 of 6 Old 07-27-2001, 06:42 PM
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Not really, as far as the noticability of the tilt goes. Think of the light as a ricochet, and it is coming out of the CRT tubes,and hitting your eyse. Set the tilt for that. The noticability of the tilt will dissapear in your perception fairily quickly. Besides, the tilt will be CORRECT for your viewing angle, so.. where does the 'looming' aspect come from? In reality, when seated, and watching a movie, it is not really there. The Ultramatte 150 is a better choice, if your PJ has lower output, like a sony 12xx series unit. It all depends. What PJ is it? Basically, if you have good night vision, and prefer perfect colorometry.. over shapr focus and depth of image, get the studiotek 130. If you prefer depth of focus for that 3-d effect, then the ultramatte 150 is the way to go. Studiotek 130 is only really suited to PJ's with at least 850 lumen output or more.

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[This message has been edited by KBK (edited 07-27-2001).]

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post #3 of 6 Old 07-27-2001, 06:53 PM
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Quote:
Originally posted by KBK:
Basically, if you have good night vision, and prefer perfect colorometry.. over shapr focus and depth of image, get the studiotek 130. If you prefer depth of focus for that 3-d effect, then the ultramatte 150 is the way to go. Studiotek 130 is only really suited to PJ's with at least 850 lumen output or more.

Ken:

Just for clarification, your statement only refers to smaller projectors? If one has a 9" projector, the colorimetry, focus, and depth will be there in the StudioTek 130?

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post #4 of 6 Old 07-27-2001, 07:13 PM - Thread Starter
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Thanks Ken,

That was pretty much what I was thinking. My PJ is a BG808s. The tubes are kind of old so I'd like the extra gain of the 150.

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post #5 of 6 Old 07-28-2001, 08:33 AM
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Not really, as far as the 9" unit goes.

You see, depth of field, or 3-d effect, is tied to sharpness/contrast depth..which CAN be a fucntion of the screen. Higher gain screens are less sensitive to being infected by the light being shone upon them, compared to lower gain screens. For instance, it is possible, to see the light in a given bright area, create a situation where there is a slight lightening of adjacent dark areas of the screen. This even happens with 1.5 gain screens.. if they are too thin a maerial, or mounted directly on a white wall as well (thin materials), for example... blackout fabric can be the worst for this effect. Matt screens (1.0 gain)are the worst in this respect (to me, they are so soft, contrastless and flat looking, they are disgusting). They have a lower contrast ratio, than that of a 1.5 gain screen.

So, the studiotek 130 is slightly less capable of producing this '3-d' effect than the ultramatte 150. It's a thing that has to be looked at on a WHOLE screen for comparison, which most people cannot afford to do, and cannot easily do, even if they have the cash to get both. Dealers get to see this effect, but only if they switch screens on the same PJ,and have a PJ good enough to see the differences, AND they are capable of making this understanding. So, the 'blocks' in finding this sort of thing out are rather hgih...I have had as much as 19 different screen formulations in the house at one time.

the reason I can, Is I am making my own screens,and screen materials (screen paints, with different gains and characteristics), So, I get the info rather often and clearly. I have changed screens three times in one day.. on numerous occasions, as this is how to assess materials properly.. no other test is valid. Full screens are the only testing method or evaluation method of any real merit.

As for the comparisons of Stewart materials, I have truthfully, incidental knowledge of such surfaces, other than the samples that Don sends out. The studiotek 130 has this 'loss in contrast depth modualtion' less than that of other 1.3 gain materials..that I have seen. It is an extremely well designed material. However, for the 3-d 'pop-out' effect, the Ultramatte 150 is superior. But, hotspotting and colorshift does begin to intrude, but to a fairly minor degree. Truth be known, it is ufair of me to make comparisons of ANY stewart materials, as I am close to being a manufaturer myself. I don't mind too much, as I am not 'dissing' Don's product in any way, they are both excellent screen materials.

The effects that I speak of are directly related to gain characteristics of materials and screens. They will affect any screen that has a gain cahracteristic, and WILL be an arbiter of what could be considered their 'ultimate image fidelity',and the directions and resultant of the choices made in that particualr design, insofar as trade-offs that are inherent in the way it was finalized.

9" CRt units are capable of throwing enough light onto a larger screen with lower gain (1.3), so the losses with contrast depth and sharpness (due to higher output) are not as readily apparent, as they would be with a 700 lumen unit, likea Electrohme ECP 4100. I would suggest a slightly smaller, higer gain screen for a ECP 4100, just to keep the pressure off the unit, the contrast modualation up, and the sharpness up. It reslts in a longer lasting PJ, with less pressure on it, and a sharper, deeper-looking image. 1.3 gain in this case, will up the pressure on the tubes signifigantly, and shorten the life of the PJ's tubes, at the same time the image softens, due to the screen,and the increased output of the PJ. I have friend who has preamturely weakened his previosuly MINT blue tube on his ECP 4000 PJ, specifically due to this sort of situation. Too low a gain, and too hiogh a pressure on the PJ.

You will get slight darkening in the corners of the image as well, due to the higher gain material, and the light drop off inherently in the tube's corners. It will be more noticable in the higher gain screen, due the fact that it is more mirror like (the screen), and you are further off axis from the corners, compared to the center of the screen...

The trick is to see diferrent screens in action, before you buy. Make a small trip to do so, if at all possible. it is wroth the effort to get the right screen for you, due to the fact that it is fully HALF the equation, when it comes to image fidelity and quality that you get.

More people should be aware of this fact. The screen is VERY important. It is FUNADAMENTALLY a LARGE part of the ACTUAL DISPLAY DEVICE.

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[This message has been edited by KBK (edited 07-28-2001).]

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post #6 of 6 Old 07-28-2001, 09:51 PM
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WOW Ken! I wasn't expecting such an in-depth response. You have addressed all of the issues plus some that were floating about in my mind.

From the setups I have seen in my area for CRT projectors, everyone is using StudioTek 130. I haven't seen the 150 material. As I mentioned in another thread, I received two different redcommendations from Stewart for my projector model. Both the 130 and 150. I'm not sure if Stewart has a display room at their head quarters open to the public? If so could take a trip down to So. Cal. I would prefer the 3-d effect and sharpenss over exacting color so maybe I have the answer now.

I don't think I want to buy 2 screens in order to make a final decision so maybe I should attempt to make a couple myself?
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