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Discussion Starter · #1 ·
Hi,

Does anyone have any experience or thoughts on these high contrast grey screens by Loch? I'm specifically looking at the Loch High Contrast 92'' diagonal Manual Projector Screen with Slow Retraction. The specs and price are attractive to me – does it sound too good to be true?

amazon.com/LOCH-92-diagonal-Projection-Retraction/dp/B00DV1J4ZM

My setup isn't ideal -- small apartment room with white walls. I only watch movies at night with the lights off.

Projector is a Benq W1070. The piicture looks great in dark scenes as well as bright scenes (nintendo video games and classic high-key technicolor movies look amazing), but get's washed out by ambient light in high contrast scenes with both a lot of white and black. Screen budget is less than
 

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Projector is a Benq W1070. The piicture looks great in dark scenes as well as bright scenes (nintendo video games and classic high-key technicolor movies look amazing), but get's washed out by ambient light in high contrast scenes with both a lot of white and black.
In my experience most grey screens do not improve contrast; they make the black look darker but cut down on the whites at the same time. From your description it appears that the washing-out is primarily caused by reflections off the white walls from the projected image itself. I would say your third option of buying a used GrayWolf would make the most improvement to the contrast, assuming you're not bothered by the "sparklies".
 

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Discussion Starter · #3 ·
I was wondering if the Loch high contrast gray material could be the same as Elune 1.1 Cinema Gray -- both screens have very similar product pictures, are manufactured in china, and have almost identical specs. The Elune, Graywolf, and Loch manual screen cases all appear to be identical. The remotes for the electric screens are the same design. I was in touch with a Elune representative about having their 1.1 Cinema Gray shipped to the US (they don't ship the cheaper manual screens here), and asked them if they shared a manufacturer with the loch screens, but the representative declined to answer. It would make sense that they wouldn't want to if it were true, given that the Loch screens are considerably less expensive.

I'm still unsure what I should do: I went ahead and ordered the Loch screen, but I also serendipitously found a Graywolf I screen over the weekend on craigslist, and I'm relatively happy with the performance. The washout from the reflected ambient light is 100% gone, and the color/contrast is great. The texture of the screen is definitely noticeable in some situations, as expected, but something I could potentially live with. I think the appearance of the texture becomes less noticeable viewed off axis, and the brightness reduction isn't a problem paired with the lumens of the w1070.

I'm faced with the dilemma of refusing the package, or opening it to test it out, potentially having to pay $40 for return shipping or reselling the Graywolf on craigslist (which shouldn't be hard given the price I found it at).

My imagined cons of the Loch screen: Inferior ambient light rejection (how much, I have no idea) and worse white clipping

Cons of the Graywolf: Texture

Any thoughts would be much appreciated! If I end up opening the Loch screen, I'll let everyone know how the two screens stack up!
 

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My imagined cons of the Loch screen: Inferior ambient light rejection (how much, I , have no idea) and worse white clipping
Cons of the Graywolf: Texture
I don't know anything about Loch screens, but in general the lower gain, non-directionalal grey screens will not give you any real ambient light rejection capability. If you can live with the occasional texture of the GrayWolf screen, I would say keep it.
 

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Discussion Starter · #5 ·
My imagined cons of the Loch screen: Inferior ambient light rejection (how much, I , have no idea) and worse white clipping
Cons of the Graywolf: Texture
I don't know anything about Loch screens, but in general the lower gain, non-directionalal grey screens will not give you any real ambient light rejection capability. If you can live with the occasional texture of the GrayWolf screen, I would say keep it.
Doesn't the positive gain of the grey loch screen indicate a non-lambertian reflectence, which would means some ambient light rejection?
 

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Doesn't the positive gain of the grey loch screen indicate a non-lambertian reflectence, which would means some ambient light rejection?
If you look at the Elunvision Cinema White and Cinema Grey screens as "representative" examples, there's essentially no difference between the two, when it comes to ambient light rejection ratios between white and grey screens:
http://elunevision.com/cinema-white.html
http://elunevision.com/cinema-gray.html

Compare these to their Pro Cinema Grey, which is the same as the GrayWolf:
http://elunevision.com/pro-cinema-gray.html
 

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Discussion Starter · #7 ·
If you look at the Elunvision Cinema White and Cinema Grey screens as "representative" examples, there's essentially no difference between the two, when it comes to ambient light rejection:
http://elunevision.com/cinema-white.html
http://elunevision.com/cinema-gray.html

Compare these to their Pro Cinema Grey, which is the same as the GrayWolf:
http://elunevision.com/pro-cinema-gray.html
Those spec sheets say that the white has an 81% ambient light reflectance value, and the gray reflects even less ambient light at 67%, no? Makes me wonder whether I should have gone with a white screen –– I imagine the white wall I was projecting on reflects ambient light even worse.
 

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Discussion Starter · #8 ·
Thanks for pointing me to these spec sheets. I guess ambient light reflectance value of the Graywolf is 51%, and I suspect that its ambient light rejection properties are overkill for my needs, where I'm only trying to fight the ambient light reflected off of my white walls. I think I'll give the screen being shipped to me a shot.
 

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Those spec sheets say that the white has an 81% ambient light reflectance value, and the gray reflects even less ambient light at 67%, no?
These are light reflectance values, which obviously will be lower for the grey screen. If you look at the actual curves, the ratio between 0-deg gain and 80-deg gain are:

Cinema White: 1.2/0.86=1.39
Cinema Gray: 1.1/0.79=1.39

The ratio for the Pro Cinema Gray is 1.8/0.63=2.86
 

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Discussion Starter · #10 · (Edited)
These are light reflectance values, which obviously will be lower for the grey screen. If you look at the actual curves, the ratio between 0-deg gain and 80-deg gain are:

Cinema White: 1.2/0.86=1.39
Cinema Gray: 1.1/0.79=1.39

The ratio for the Pro Cinema Gray is 1.8/0.63=2.86
I believe you're incorrect, those graphs do not describe "ambient light rejection" as a property, they simply are mapping the gain over the viewing angle. Gain refers to how much light is reflected w/ respect to a lambertian surface. The Vivid Pro Cinema Gray will reflect much more light back at the viewer than either the Cinema White or Cinema Gray, yet it has the lowest Ambient Light Reflectance value because it has the highest "ambient light rejection" (which is not a real metric).

A gain of higher than one indicates that more light is being reflected back in the direction of its source, instead of being diffused evenly at all angles, which is essentially ambient light rejection.
 

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I believe you're incorrect, those graphs do not describe "ambient light rejection" as a property, they simply are mapping the gain over the viewing angle.
Yes, these curves indeed show how the gain varies with the viewing angle.

Note, however, an ALR screen only rejects ambient lights coming at an angle, and it works by having a higher gain at 0 degrees and a lower gain at steeper angles. It has no other way for distinguishing between the projected light and the ambient lights.

Thus, you can tell a lot about the light rejection capability of a screen by looking at its gain-vs-angle plot. A lambertian surface (with a uniform gain for all angle) will have NO ambient light rejection capability. Conversely, a screen with a steep curve (such as the Pro Cinema Gray) is very effective for ambient light rejection.
 

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Discussion Starter · #12 ·
Thus, you can tell a lot about the light rejection capability of a screen by looking at its gain-vs-angle plot. A lambertian surface (with a uniform gain for all angle) will have NO ambient light rejection capability. Conversely, a screen with a steep curve (such as the Pro Cinema Gray) is very effective for ambient light rejection.
Yes, and neither the Cinema White or Gray screens are lambertian surfaces, and it appears that they will exhibit some ambient light rejection properties as shown by the slope of the curve on their spec sheets. The Ambient Light Reflectance value also indicates that the Cinema Gray reflects less ambient light at the viewer than Cinema White, and the Vivid Pro Cinema Gray reflects the least ambient light. Looking at the gain-vs-angle plot seems helpful in evaluating ambient light rejection ability, but I don't think showing that the ratios between the highest and lowest gain on the Cinema White and Gray are the same indicates much -- of course they're equal, the slope is the same.
 

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The Ambient Light Reflectance value also indicates that the Cinema Gray reflects less ambient light at the viewer than Cinema White, and the Vivid Pro Cinema Gray reflects the least ambient light.
It goes without saying that a grey screen will have a lower Ambient Light Reflectance Value (ALRV) than a white screen. What I have been saying, is that a lower ALRV does not necessarily indicate a more "effective" ambient light rejection.

For example, the Elunevision Perlux-Silver screen has better ambient light rejection than the Cinema Gray screen, in spite of a higher ALRV (0.78 vs. 0.67). According to Elunevision themselves, the Perlux-Silver has "High resistance to ambient light" whereas for the Cinema Gray they say "Controlled lighting recommended"'.

What matters is the ratio between the projected image and the ambient light.
 
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