Simple Way to See if You'd Benefit from JVC Black Levels

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 or 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.
Edited by sarangiman - 1/25/13 at 12:11pm

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...

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.

Is that your auto-iris at work?

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.

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.

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.