Simple Way to See if You'd Benefit from JVC Black Levels - AVS Forum
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post #1 of 19 Old 01-22-2013, 12:45 PM - Thread Starter
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Simple question for you all:

People keep wondering whether or not they'd benefit from the black levels of a JVC even in a room that isn't very well light-controlled (light ceilings/walls, e.g.).

Well, isn't this a simple way to tell if your setup would benefit from a projector with better black levels:

On a 16:9 screen, put up 2.35:1 content. Put your hand up in the light path so you see its shadow on the bottom black bar. IF you see a significant shadow of your hand, then you'd benefit from a projector with better black levels. IF you don't, you probably have a JVC wink.gifor you have so much ambient light/reflections that the black level of the projector is of little consequence.

I know this test depends on a # of factors; e.g. the shadow of my hand is much dimmer when the iris on my Sony HW50 is clamped down. But I can see it quite well when the iris opens up (not even fully, since I have max iris clamped down to 2/3 stop dimmer than fully open using 'Auto Limited'). I've attempted to combat room reflections by going with a High Contrast High Power (HCHP) screen, added Protostar material (only 30" out from screen) on my ceiling, & limited my iris so that it's never fully open.

But there are still room reflections I can see (ceiling further out, floor, etc.)

Still, I can see the shadow of my hand pretty well when the iris opens up. Since this shadow on the screen still experiences the same reflections as the black bar right next to the shadow of my hand, doesn't that mean I'd benefit from the projector putting out less light in that black bar area?

Pretty sure the answer is an obvious 'yes!', but I just wanted to get people's feedback.

Thanks.
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post #2 of 19 Old 01-22-2013, 01:51 PM
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I've run my previous HD350 in the same room in two different guises: One being the native decor with a white ceiling, light grey walls and an Oak floor. The other being with the walls and ceiling covered with a black cloth 'tent' and every light piece of furniture and flooring near the screen covered up with similar black cloth or dark throws. I measured a 3x improvement in ANSI contrast and for sure the image looked better in the treated room, however in really dark scenes I still benefit from the JVC's black levels in the untreated room. I've since upgraded to the X35 and see better contrast still, though I do intend to improve the room to take more advantage I've certainly noticed the improved black levels over my HD350. I don't seen why others wouldn't benefit from the better black levels unless they insist on watching with some lights on in which case I'd say go for a brighter projector such as the Sony.

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post #3 of 19 Old 01-23-2013, 04:50 PM
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Quote:
Originally Posted by Kelvin1965S View Post

I don't seen why others wouldn't benefit from the better black levels unless they insist on watching with some lights on in which case I'd say go for a brighter projector such as the Sony.

There can be uncontrolled ambient light even with all of the lights off; some people's rooms contain transparent building materials. smile.gif

IMO the test is brilliantly simple.

Noah
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post #4 of 19 Old 01-23-2013, 05:17 PM - Thread Starter
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Originally Posted by noah katz View Post

There can be uncontrolled ambient light even with all of the lights off; some people's rooms contain transparent building materials. smile.gif

IMO the test is brilliantly simple.

Yeah my point is that if you have so much ambient light/reflections that putting your hand in the light path to try & create a shadow in the black bar region of a 2.35:1 movie doesn't create much of a shadow, then you're likely not going to benefit much from a projector with lower black levels.

Why? Simply because ambient light/reflections are raising the black floor of your image so much that lowering the black floor of the projected image wouldn't help much b/c the actual amount the signal (from the projector) would decrease with a higher contrast projector would be insignificant compared to the 'signal' of the ambient light/reflections.

Let's play with some numbers:

Let's say that the ambient light + reflections in your room raise the black bar to a signal of 200, even though the actual black projected onto the screen by your projector prior to ambient light/reflections was 20. If you now get a projector with 10x better native contrast (e.g. a JVC over a Sony), then the projected black prior to ambient light/reflections would be 2 (for equal highlight value between both projectors). Since ambient light/reflections was adding a signal of 180, we get a black floor now of 182. That's only a drop of 9%. Probably pretty insignificant.

In reality, though, I doubt most people have such bad ambient light/reflections, and so would benefit from a higher native contrast projector.

But if you like watching with lots of ambient light, this is a quick test that I think is valid...
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post #5 of 19 Old 01-25-2013, 08:25 AM
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I think if you like watching in ambient light then you should buy a big TV, but that's just me. tongue.gif

I get what you're saying about the shadow puppets, but there isn't a projector yet made that won't produce some shadow puppets in the black bars (even a HD990/RS35) still had quite visible 'black bars' when I saw one in a completely black walled room for example). However, it's a good guide to see if there is too much ambient light or room reflections. If it's the later, then you still benefit from the better fade to black and in very dark scenes with a JVC as I've found...I would like to further improve my room though to get even more benefit.

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post #6 of 19 Old 01-25-2013, 09:27 AM
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No matter how great the room is and how great a digital front projector (at maximum present levels) hand puppets will always be visable. Massive improvements in digital projection need to be realized to make blacks truly black. That said, a higher on off contrast level will aways be beneficial for a variety of reasons. these reasons have been thoroughly discussed and are perhaps best explained by darin's paper several years ago. the question of how much weight vs other parameters of projector performance becomes a rather sunjective discussion without personnel preferences coming into play and they must come into play. unfortunately, while simple tests can be used to see some of the benefits of increased on off numbers, others can not be seen that easily. Likewise many other performance improvements require a rather sophisticated viewer and tests which most just don't understand.

this is a good thread and i applaud the thread starter and the valuable observations of others here.

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post #7 of 19 Old 01-25-2013, 12:15 PM - Thread Starter
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Thanks Mark, & Kelvin.

Agreed. Most everyone would benefit from a higher contrast projector. Just not if you're watching with a ton of ambient light in a white room with a huge matte white screen close to white walls/ceilings... where the 'signal' of everything else (ambient light/reflections) is so high that the change in black level from a higher contrast projector would be masked by said overwhelming ambient light/reflections.

But, in that case, sure... you should own a TV!

All that being said, when my Sony HW50 clamps its iris down in dark scenes, it does take me a couple seconds to find the shadow of my hand. So that's pretty damn good... and I'm happy about everything I've learned on these threads & in Darin's paper (thanks Mark) about controlling reflections & about all the various screen materials, etc.
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post #8 of 19 Old 01-25-2013, 01:35 PM
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I just left my Oppo player in pause for a while and then the white 'Oppo' text floats around the screen. When it's present the black background is clearly dark grey,but when it goes off the edge of the screen for a brief second the screen goes jet black.If I make a shadow at this time I can't see it for the brief time the text is off the screen. It's surprising how much lighter the background gets even with a tiny bit of white present.

Anyway, off to watch some films...in the dark. smile.gif

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post #9 of 19 Old 01-25-2013, 02:26 PM - Thread Starter
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Quote:
Originally Posted by Kelvin1965S View Post

I just left my Oppo player in pause for a while and then the white 'Oppo' text floats around the screen. When it's present the black background is clearly dark grey,but when it goes off the edge of the screen for a brief second the screen goes jet black.If I make a shadow at this time I can't see it for the brief time the text is off the screen. It's surprising how much lighter the background gets even with a tiny bit of white present.

Anyway, off to watch some films...in the dark. smile.gif

Is that your auto-iris at work?
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post #10 of 19 Old 01-25-2013, 03:22 PM
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No iris on the X35. That is the effect of reflections in the room back to the screen.

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post #11 of 19 Old 01-25-2013, 07:34 PM
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Or you can get an old CRT projector.smile.gif

I got to do this test with a CRT projector (Sony G90) a JVC and a 70mm film projector from a movie theater. The CRT projector had minimal or no shadow which is not surprise, the JVC did. And to my surprise the 70mm projector from your typical movie theater had a shadow as well.

Not trying to hi jack this thread or cast aspersions, but I agree, this is a valid test. Gives credence to darkening all rooms. The fewer reflections the better for any viewing.

No kidding, a fellow AVSer had all three set up at the same time. The 70mm projector was in the dining room throwing the picture through a hole in the dining room wall. Really a cool demo.

i would have thought the 70mm film projector would have been the least of the three.

Live and learn.

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post #12 of 19 Old 01-30-2013, 02:43 PM - Thread Starter
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Just confirmation of the validity of this test:

Last night I left some minimal lights on in the room (some Christmas lights) for some 'ambient light'.

Checked the shadow of my hand on the black bars... could barely see it.

Turn off the lights, & yup, I can see the shadow again.

So in my scenario:
  • With a little bit of ambient lighting from my Christmas lights, I wouldn't benefit much from a projector with higher native contrast, b/c ambient reflections kill the contrast enough that lowering the black floor of the projector is insignificant next to the overwhelming 'signal' adding to blacks from my ambient lighting.
  • With all lights off, & minimal ambient lighting, I'd definitely benefit from a projector with higher native contrast.

Nothing surprising/earth-shattering here. Just confirms that this is a simple quick test you can perform if you're curious.
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post #13 of 19 Old 01-30-2013, 03:19 PM
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Time you took your Christmas lights down as I've already seen Easter eggs on sale. biggrin.gif

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post #14 of 19 Old 01-30-2013, 03:47 PM - Thread Starter
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Originally Posted by Kelvin1965S View Post

Time you took your Christmas lights down as I've already seen Easter eggs on sale. biggrin.gif

Haha. I think I'm going to get some 'up lamps' that AVS user airscapes mentioned. Just don't like having the entire room dark. If the up lamps can provide a thin column of light shooting up in the corners of my room, perhaps that light won't bleed onto the screen? We'll see.
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post #15 of 19 Old 01-31-2013, 12:33 AM
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I have to watch in the complete dark, that way you get the best black level and fade to fade seems (momentarily) pitch black. Each to his own though.

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post #16 of 19 Old 02-04-2013, 10:19 AM
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I have to watch in the complete dark, that way you get the best black level and fade to fade seems (momentarily) pitch black. Each to his own though.

I'd have to agree. Don't like watching in the dark? Get a brighter projector and a higher gain screen !! smile.gif

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post #17 of 19 Old 02-04-2013, 11:52 AM
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If the picture on the screen is bright, wouldn't the black bar test be more a test of ANSI rather than native contrast? Wouldn't a bright scene lead to more of a shadow than a dark scene? And I thought that JVC was stronger at native than ANSI contrast.
The test makes more sense if you were to specify that the picture should be showing 3 bright stars on a black background, for example, since that's the visual where JVC is said to have the edge.
For black bars, I thought the main cure was still masking, not projectors, because all of them project non-black bars.
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post #18 of 19 Old 02-18-2013, 04:09 PM - Thread Starter
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Quote:
Originally Posted by A.West View Post

If the picture on the screen is bright, wouldn't the black bar test be more a test of ANSI rather than native contrast? Wouldn't a bright scene lead to more of a shadow than a dark scene? And I thought that JVC was stronger at native than ANSI contrast.
The test makes more sense if you were to specify that the picture should be showing 3 bright stars on a black background, for example, since that's the visual where JVC is said to have the edge.
For black bars, I thought the main cure was still masking, not projectors, because all of them project non-black bars.

That's a good point, but my initial goal of this test was to see whether or not you'd benefit from a higher native contrast projector based on your room setup (of which the main factors are: (1) ambient light, and (2) reflections/scattering of light from screen to walls/ceilings back to screen).

So, actually, for this test I would suggest throwing up a bright scene. Yes, the test conflates ANSI contrast & ambient light/reflections in determining if you should get something with better native contrast. I fully concede that.

But, for a lot of people, I'm willing to bet ambient light/reflections kill contrast much more than ANSI contrast of the projector itself. Unless you have a bat cave.

But thank you for making your point, as it is definitely a valid one.
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post #19 of 19 Old 02-12-2014, 09:51 PM
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Originally Posted by sarangiman View Post


All that being said, when my Sony HW50 clamps its iris down in dark scenes, it does take me a couple seconds to find the shadow of my hand. So that's pretty damn good...

It takes a few seconds for your "auto irises" (one in each eye) to open up enough to see the shadow of your hand.

The darker the environment (i.e., less reflective), the more irises in people's eyes will open up when a very dark scene is viewed for sufficiently long amount of time. The irises close quickly (for protection of retinas), but open up more slowly (and extremely slowly to a large diameter). This opening of irises reduces the perceived black level.
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