DVX 100A Black Level Set up

Bob Hayes · November 1, 2004

Where should the black levels be set on a DVX 100A for NTSC broadcast (0 or 7.5). I set my PD150 at 7.5 and like the look.

Jon Allen · November 1, 2004

I usually set mine for 0, which gives the greatest actual recorded black levels. Then I pull a color corrector and make sure nothing's too bright and nothing's too dark before I send it out. You can also add a "broadcast safe" filter to the whole thing in post if you want to.

I've found that paying attention to the vectorscope in post does an adequate job.

Alvin Pingol · November 2, 2004

I too set mine for 0, which I like because like Jon said, gives you the greatest actual recorded black levels. In other words, it gives you a bit more dynamic range since you can capture details in the shadows that would be lost had 7.5 been used.

Sure, maybe these details won't show up if the material is broadcasted, but I feel that if someone's work is significantly worsened due to a loss of detail in the 0 through 7.5IRE range, perhaps that person should worry less about setup levels and more about lighting!

Phil Rhodes · November 2, 2004

Hi,

Theoretically this should be a technical issue, not about liking the look. In the US, technically, all your material should be mastered with 7.5IRE setup. This does not mean that it has to be shot and postproduced with setup, and if you shoot with Japanese-style NTSC (no setup) you are maximising the capability of the DV format. Using this setting as an artistic way to affect black levels is theoretically wrong, in that it will put the black level of your picture closer to the bottom of sync than it should be - not that it is ever likely to cause any actual problems.

Phil

Jon Allen · November 2, 2004

I have a question- does HDTV still retain a 7.5 IRE setup?

Preston Herrick · November 3, 2004

Like Phil said, this is a technical issue. Shoot at 0 IRE (the standard of all DV including HD). When it hits an analog stage (like VHS dupe, BetaSP, whatever), add setup. When your DV material hits a broadcaster they'll adjust their proc amps so that black starts and 7.5 for the NTSC world. In my opinion, if you shoot at 7.5 you'll create headaches for yourself down the road in other areas.

Edited November 5, 2004 by PrestonHerrick

Michael Nash · November 3, 2004

I agree that it's a technical issue. As far as "liking the look," just make sure the monitor you're using is set up for the black level of the camera. That way what you're seeing (and liking ;) ) is what will end up in the finished product -- assuming someone doesn't add additional setup if you're shooting with 7.5 black.

Alvin Pingol · November 5, 2004

assuming someone doesn't add additional setup if you're shooting with 7.5 black.
<{POST_SNAPBACK}>

Hmm... wait a tic. Now, would that actually change anything? I mean, if setup is 7.5-IRE on tape, does that mean 7.5-IRE becomes the "new 0-IRE?" Or, is it simply there is no image recorded (i.e. black) within the 0 through 7.4999-IRE? If the latter, adding another setup over that shouldn't change anything, since there wouldn't be anything in that range anyway... right?

If the other case (7.5 becomes the new 0), then what's the use of setup levels anyway, if you're just going to stretch out 7.5 through 100, to 0 through 100?

Agh.

Michael Nash · November 5, 2004

Or, is it simply there is no image recorded (i.e. black) within the 0 through 7.4999-IRE?
<{POST_SNAPBACK}>

That's it. For NTSC, 7.5 IRE represents the darkest visible black. As in shooting-with-the-lens-cap-on black. 0 IRE is called "superblack," and is not visible.

Adding 7.5 IRE of luminance to an image that already has 7.5 as the blackest black the camera can render, means the black now becomes 15 IRE. That's not black; it's foggy gray.

Jon Allen · November 5, 2004

I saw a commercial this week (for dodge) and it was obviously done incorrectly. I pointed it out to my wife, but she didn't notice even after I showed her- yeah, I married a non-videohead.

There was supposed to be some glow around the CG on top of some black bg, the glow stopped short and didnt dissolve correctly. Another victim of poor IRE setup.

Alvin Pingol · November 7, 2004

That's it. For NTSC, 7.5 IRE represents the darkest visible black. As in shooting-with-the-lens-cap-on black. 0 IRE is called "superblack," and is not visible.

Adding 7.5 IRE of luminance to an image that already has 7.5 as the blackest black the camera can render, means the black now becomes 15 IRE. That's not black; it's foggy gray.

<{POST_SNAPBACK}>

Thanks Michael. I googled some websites dealing with setup levels. Now it makes complete sense. :-)