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    Help: how to use the zebra stripes?
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    Member Tom Knight's Avatar
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    I'm a new user, and am figuring out the camera, little by little.

    Maybe this is already posted somewhere, but I can't figure out how to use the zebra stripes. I can hit the buttons and see it on the screen, but what does it mean? And how should I adjust the iris?

    Thanks!
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    Moderator Alex H.'s Avatar
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    Zebras are there to show areas that are overexposed, or close to overexposed. You can set the sensitivity of the DVX's zebras in 5% increments from 80% to 105% in the Display Setup menu. At 100%, the zebras are showing areas that are at 100IRE (the top of the waveform monitor in your NLE). Exposure should be kept just below that.

    I tend to keep my zebras set lower - 85% - because it's much easier to correct for a slight underexposure. Once highlights are blown, the detail is lost and you'll never get it back.

    To use zebras for setting exposure, bring the exposure up to the point that the zebra patterns just start to show in the highlights (if you have them set to 100%), then dial the exposure back just a touch.. If you're using something like 85%, you can expose with a little bit of zebra pattern in the highlights.
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    Caucasian skin should never trigger more than maybe 75 zebra IRE in the most highlit areas. 70 is safer. If you set your zebras to 70 and then expose such that you only just barely get the very slightest hint of zebras on your subject's skin, you'll have proper exposure.

    Then, you want to go checking for highlights to make sure nothing's blown out. I use 100 IRE for that, but you can certainly use other levels. So I set my two zebras at 70 and 100; check skin at 70, and check for blowouts with 100. If you only get a tiny bit of zebras on the skin at 70, and none anywhere in the scene with 100, then you've probably got an excellent exposure.


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    Member Tom Knight's Avatar
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    Thanks guys!

    I'm honored that Barry Green himself is answering a question. (I'm reading your DVX book and watching the DVD.)

    - Tom
    http://www.youtube.com/user/tomknightproductions
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    Quote Originally Posted by Barry_Green View Post
    Caucasian skin should never trigger more than maybe 75 zebra IRE in the most highlit areas. 70 is safer. If you set your zebras to 70 and then expose such that you only just barely get the very slightest hint of zebras on your subject's skin, you'll have proper exposure.

    Then, you want to go checking for highlights to make sure nothing's blown out. I use 100 IRE for that, but you can certainly use other levels. So I set my two zebras at 70 and 100; check skin at 70, and check for blowouts with 100. If you only get a tiny bit of zebras on the skin at 70, and none anywhere in the scene with 100, then you've probably got an excellent exposure.
    barry-

    as always, thanks for adding to the conversation.

    on my dvx100b, the lowest option under the zebra menu is 80.

    is there another way to set the zebras as low as 70?

    thanks in advance.

    be well

    rob
    smalltalk productions


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    i always set my zebras to 80% and adjust my iris as bright as possible without zebras forming on anything important. ie a white projector screen or top pf podium right where a bright light is focused can have zebra. I make sure faces have no zebra at 80 and am generally ok.
    Last edited by Richter Video Equipment; 05-18-2011 at 03:14 PM.


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    #7
    Member Tom Knight's Avatar
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    This is very helpful! Thanks!
    http://www.youtube.com/user/tomknightproductions
    Still kind of new at this stuff...
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    Moderator David Jimerson's Avatar
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    Quote Originally Posted by Richter Video Equipment View Post
    i always set my zebras to 80% and adjust my iris as bright as possible without zebras forming on anything important. ie a white projector screen or top pf podium right where a bright light is focused can have zebra. I make sure faces have no zebra at 80 and am generally ok.
    If you're exposing well-lit white, like a shirt or paper, at 80% or lower, you're really cheating yourself out of a chunk of dynamic range. To squeeze maximum range out of the camera, better to set the top zebra at 100 or at least 95 and then keep the zebras off.

    Everyone has their preference, but stopping down that much really is keeping the camera from doing the best of what it can do.
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    Quote Originally Posted by David Jimerson View Post
    If you're exposing well-lit white, like a shirt or paper, at 80% or lower, you're really cheating yourself out of a chunk of dynamic range. To squeeze maximum range out of the camera, better to set the top zebra at 100 or at least 95 and then keep the zebras off.

    Everyone has their preference, but stopping down that much really is keeping the camera from doing the best of what it can do.
    I think it really depend on how reliable the lighting is. the lighting guys at the school i sometimes work for suck, so i'd rather air on the side of caution and be a little low. I generally tape lectures. If taping dance or theater its more important to be dead on.


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    Moderator David Jimerson's Avatar
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    Does the lighting change during the lecture? If not, set your exposure and you're good to go.

    Now, two things are true -- in that specific situation, pushing the camera to be its best may not be as important (but why not do it anyway?), and it's better to underexpose than overexpose with video. But for typical exposure, whites really should be in the 90-100 range.
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