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    Zebra confused

    I did a search and read the examples on using Zebra and I am still confused. Here is my question - I am setting up a martial art instructional and relied on 100 Zebra setting. I let a small amount of Zebra on the brightest highlight. Is there another way to go? Also, what is with the 80 Zebra setting and when do you use it in my case?

    Do I need to use a light meter? I already use my monitor that I edit on. what are the advantages of using the light meter vs the Zebras?

    #2
    Per Barry Greens DVX Manual:

    Set the Zebra for 80%. Anything that is over that; 100% or 105% for example should be measured for 'highlights' such as the sun or light bulbs. Use Zebra 1 at 80% and Zebra 2 to protect against blowouts.

    Get Barry greens book if you do not have it already.

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      #3
      OK. I will get the book. In the meantime, I should test the Zebras at setting 1, and then at 2?

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        #4
        I would suggest you use only one zebra. If you set it at 80% you would be doing so because faces over expose beyond 80%. But in your case the martial arts white will be of more concern so I'd set your zebras at 100 units. Then you will know that if you see ringing on their uniforms, its is over exposed. Faces will expose fine in this case. THe double zebra gimmick came about some years ago and its more confusing to have two sets of zebras going then one. All yo need to be concerned with is that white isn't overexposed. Doing so in such a scenario as you described will do all you need.

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          #5
          That is a good point Walter; and I missed that. I agree and admittedly never use 2 Zebras. Damn the Scriptures.

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            #6
            Advising someone to discard the 80% zebra setting, especially when they are new and/or shooting something with a large percentage of white in the shot, is cavalier and perhaps will lead to improper exposure. There are very good, very valid reasons why there are two zebra settings!

            If someone already knows how to shoot, and already knows how to use zebras, and knows what a properly-exposed shot looks like, then the 80% setting is used much less frequently. But for a poster who's asking the question, then obviously they're not at that level yet, and the 80% zebra is a valuable tool for someone in that situation.

            80% is what you use to check for exposure on your subject's faces. Actually 70% would probably be better. At 80%, the very brightest highlights on your subject's faces would just barely trigger the 80% zebras (in a normally-composed, properly-exposed shot). The 100% (and, preferably, 105%) zebras are used to watch for and prevent blown-out overexposure.

            If you were to rely solely on 100% zebras, especially in a situation with white clothing dominating the shot, there's a very good chance that your exposure on your subjects would be way too dark. With video you can't just go about exposing for the highlights and hoping/praying that that means your shot will look okay! You have to know where, brightness-wise, your image is at. 80% lets you see a second reference point.

            If you went around using only 100% zebras as a guide, you'll probably end up with some signfiicantly underexposed shots in many circumstances, especially outdoors. You have to have some idea of the overall exposure level in your shots, not just on the brightest highlights. You may find that you need to bring up the light level on parts of your subject. You may find that there is no way to avoid blowing out some highlights if you want to get proper exposure on your subject. And you won't know that if you don't know what the overall exposure level on your subject is.

            80% zebras is a way to find that (as is a waveform monitor and a properly-calibrated production monitor). 80% zebras are a very useful tool, ESPECIALLY for beginning shooters, and can't possibly be dismissed as a "gimmick". Once you have a lot more experience and know what your shots should look like, you may find yourself using 80% zebras less, but for beginning shooters who are learning how to control exposure, balance highlights with overall exposure etc., 80% zebras are a vital tool.
            ..
            The AU-EVA1 Book - The DVX200 Book - The UX180 & UX90 Book - Lighting For Film & TV - Sound For Film & TV

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              #7
              ok. Now I am still confused.

              If the White Gi's (clothing) are prone to overexposure, would not the 80 Zebra take care of that? Also, would not it not depend if I am using soft lights (Chimeras) on the subject rather than hard ones?

              How do I balance the faces of the subjects with the clothing? Do I take the zebra for the white clothing, then the faces, and then average?

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                #8
                The White of the Gi's will most likely trigger the 100% IRE whereas the Skin Tones the 80% IRE. If you rely on the 80% for the White of the Gi you are looking at underexposing the haiti out of the shot.

                Right Barry? Barry?

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                  #9
                  Yes John is correct. The answer I gave was more of a general purpose answer as to why someone would want to use both zebras, and not specifically tailored to your martial-arts situation.

                  You use the different zebra settings for metering different elements in your shot. The 100%/105% zebras are not for setting exposure on faces, they're for checking against blown-out highlights. Not for setting overall exposure.

                  The 80% zebras are used for setting overall exposure on faces (and even then, they're a little high, should be 75% or maybe 70%). If you set your exposure based on 80% on the white outfits, then yes, your whole shot would likely be underexposed.

                  Ideally, as a goal, you're looking to get your subjects exposed with an adequate amount of light, while not letting the highlights overexpose and clip (or "blow out"). You want to control exposure so that the highlights and dark areas fall within the range of what the camera can resolve. Using just one zebra setting makes that pretty darn hard under many circumstances.

                  So you use 80% to check your face exposures -- almost nothing on your subject's face should trigger zebras except the very brightest highlight spots, perhaps the center of the forehead or the tip of the nose or cheekbone. If no zebras are showing at all, you're probably underexposing. So you open up the iris until you just start to see the beginnings of zebras on those hotspots on the face. Next, you switch over to 100/105% zebras, and look for blown-out highlights. If you see no zebras at 105%, then you're probably at proper exposure and ready to shoot. If you see lots of zebras, that's when you know you have a problem -- and you'll have to solve it in one of several ways -- either bringing down the light level on the overexposing parts, or lowering your overall exposure (which will mean underexposing on your subject), or adding light to your subject so you can bring down the iris and keep your subject properly exposed while not overexposing the highlights. Finally, if you can't make any of those changes, you can choose to just live with it, deciding whether it's more important to you to have proper face exposure, or to avoid blown-out highlights. Each shot, and each shooting scenario, may be served better by assigning different priorities to those considerations.

                  By using both 80% and 105%, you can do that. By just using 105%, and looking at the LCD, you have no feedback on your overall exposure level, and may be very surprised (and disappointed) once you get back to the edit bay and view your footage on a television. Sure you may avoid clipping, but you may sacrifice the rest of the picture just to avoid a little section of blown-out highlights. Was it worth it? Too late now, because you already committed to it. Whereas if you use both tools (or, even, all three, bringing the "marker" function into the equation) you can make much more informed decisions.

                  It's hard at first, it gets easier with time and experience. After you've been doing it for a while, you'll get a feeling for what the exposure should be, what a properly-exposed shot looks like in the viewfinder, and when something's too hot or too dark (even without looking at the viewfinder; just judging it by looking at it live). But until you get to that point, use the zebras to develop your skillset.
                  ..
                  The AU-EVA1 Book - The DVX200 Book - The UX180 & UX90 Book - Lighting For Film & TV - Sound For Film & TV

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                    #10
                    Thanks Barry for the detailed breakdown. I never use more than one set at 100% and expose generally for the highlights; but have ran into issues in post when color correcting (I always increase contrast). I'm going to start using both; 80% for skin tones and 100% for highlights to achieve greater control in my exposure.

                    Still learning.

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                      #11
                      Barry, your book is a big help, but explanations like the one above are what I really need!!! Please consider a book and DVD covering these kind of "when/how to use" various DVX settings. Your book seems mostly about what all the different settings do, but that is like giving me a map and not telling me where the cool destinations are. Sure I can drive around and find some cool spots, but more info is really needed to make the day productive. Having said that, I am going to read your book again this weekend and see what I missed/forgot from the first reading. Hopefully my comments here are not too far off base.
                      The only second chance we get in life is the chance to make the same mistake twice.

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                        #12
                        Barry I have shot oddles of these types of martial arts videos over the years and it is not dangerous whether you know what you are doing or not. The ratio of contrast of any "white" face to truly white clothing mathematically will always be in range in such situation so that if you simply worry about the white clips, your faces will always be fine. And even if your faces were slightly over exposed, its not a problem the more important action is the movement and the person as a whole so we'd want to make sure the whites stayed legal. If you are ever in NY attend my lighting seminar and I'll show you how faces in such situations are of less concern than you think and how mathematically they'd never be as much of a problem as you think.

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                          #13
                          When using the waveform monitor in Vegas in post, I uncheck the 7.5 setup box and RGB box, and nominally tweak (using offset) the lowest luminance values to around 7.5 IRE, and use gain to tweak the highlights to around 100IRE. But I am not certain this is exactly the correct way to go about this. Is this correct? Could someone specify (briefly) the nominal procedure to follow using the wfm in Vegas? Thanks in advance.

                          Comment


                            #14
                            Originally posted by kmcgrath
                            When using the waveform monitor in Vegas in post, I uncheck the 7.5 setup box and RGB box, and nominally tweak (using offset) the lowest luminance values to around 7.5 IRE, and use gain to tweak the highlights to around 100IRE. But I am not certain this is exactly the correct way to go about this. Is this correct? Could someone specify (briefly) the nominal procedure to follow using the wfm in Vegas? Thanks in advance.
                            If you are playing your video on a regular set and shooting with 7.5 setup then you would want to check 7.5 to add the setup. And then if need be you can alter levels to suit. Remember this, not all video has to peak at 100 nor be at 7.5. If you shot a white wall you'd obviously be touching 100 but there would be no blacks so you'd see no levels at 7.5. ANd the same is true the other way. If you are shooting a dark scene and the most you get is 80 units of video then adjusting the top to 100 is going to wash out your blacks. Good to see that you are checking though. It will assure you proper playback on aTV.

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                              #15
                              Thanks for the quick reply! I have my DVX set to no setup (I think this is correct, based on Barry's DVX book???) and shoot my video ultimately to burn to dvd and watch on my NTSC TV. So should I check the setup box in Vegas wfm (even though my DVX is set to no setup), and then nominally set my lowest luminance to IRE 7.5 (or IRE 0??) and my max to IRE 100? I realize that I usually won't have this full luminance range in the video, but if I am setting the lowest (highest) luminance levels, is this the correct procedure setting to 7.5 IRE (100 IRE) with the setup box checked and my dvx set to no setup? Thanks again, this aspect of tweaking luminance is very fuzzy to me.

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