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    #31
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    Quote Originally Posted by visceralpsyche View Post
    Set your zebras to 80% IRE in the case of the GH5's V-Log implementation, and you will accurately know where the exact clipping point is. Stop down until those zebras just disappear. Voila. ETTR done
    Only if you don't care about the color fidelity of your brightest objects!

    If you were to try that technique on a shot where caucasian skin is the brightest object in the scene (a dark-haired person in a dark scene perhaps) you'll probably find that your skin tones have shifted all to yellow. 80 IRE on VLOG-L is absolute clip -- it's higher, relatively, than 105 zebras are on a normal gamma.

    Remember that the IRE is a cumulative formula, made from the individual brightness of the R, G, and B channels. If an object is primarily red or primarily blue, then that red or color channel stands a very high prospect of being clipped when the IRE brightness is that high.

    Your technique would probably work better if you set the zebras to 75, so at least whatever the hottest object is has a prayer of not having at least one if not two color channels clipped.


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    #32
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    Quote Originally Posted by joe12south View Post
    I think what he is saying is that he uses a grey card under the same lighting as the subject. Expose for that known value and the skin will be where it is supposed to be. If I misunderstood, please correct.
    Yup, got that part. I'm more curious about actual values and ranges when using false color and zebras for the grey card, and specifically how to approach that with Vlog as opposed to a standard profile.

    ETTR has you basically just worrying about the brightest part of the image, but the other approach has you using zebras for a grey card/white card and false color as well...I'm assuming?


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    #33
    Senior Member visceralpsyche's Avatar
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    Quote Originally Posted by Barry_Green View Post
    Only if you don't care about the color fidelity of your brightest objects!

    If you were to try that technique on a shot where caucasian skin is the brightest object in the scene (a dark-haired person in a dark scene perhaps) you'll probably find that your skin tones have shifted all to yellow. 80 IRE on VLOG-L is absolute clip -- it's higher, relatively, than 105 zebras are on a normal gamma.

    Remember that the IRE is a cumulative formula, made from the individual brightness of the R, G, and B channels. If an object is primarily red or primarily blue, then that red or color channel stands a very high prospect of being clipped when the IRE brightness is that high.

    Your technique would probably work better if you set the zebras to 75, so at least whatever the hottest object is has a prayer of not having at least one if not two color channels clipped.
    Yes, this is a fair comment I've often thought about using 75% IRE as my suggested clipping point for V-Log. In fact I recommend something similar for my Cine-D settings on the GH5, using 100% IRE as the zebra point to give a bit of headroom for saturated bright colours, for the same reason.

    I think I might recommend 75% IRE for my V-Log settings to give a similar amount of headroom, since not everyone is aware of the skintone issue at near clipping.

    Cheers,

    Paul
    Paul Leeming
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    Visceral Psyche Films
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    #34
    Senior Member wschmid's Avatar
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    To the question of the base iso... what do you find in the net? A lot of statements - most see the base iso for both the GH4 and the GH5 at ISO 400.


    The GH4 native ISO is 800 according to Panasonic. It’s definitely the best option when shooting V-log. I think a native ISO of 400-640 would be more appropriate for 4K in the other picture settings.
    http://www.mkeproductionrental.com/g...o-tips-tricks/

    The base ISO for VLog-L is ISO 400.
    http://cheesycam.com/panasonic-gh4-v...ore-and-after/

    While using the V-Log L profile the new base ISO is 400, not 200, so make sure to bring some ND filters along of you are shooting daytime exteriors.
    https://www.eduardoangel.com/2015/09...vlog-tutorial/

    Panasonic GH4 has ISO 400 in V Log L
    http://www.4kshooters.net/2015/06/19...nic-g7-review/

    Nick states that the GH4 VLOG L base ISO is 400 and 800 looks great
    http://eriknaso.com/2015/07/08/gh4-v...wood-for-clip/

    As a result, the GH5’s base ISO is 800 (a figure misattributed to the GH4 in an interview with one of Panasonic’s Japanese executives).
    https://suggestionofmotion.com/blog/...panasonic-gh5/

    Bemerkungen zur Base ISO 400

    Die Base-ISO der Kamera liegt in V-Log bei 400. Diese Erkenntnis fällt bei der GH5 besonders leicht, da die Kamera auch mit Gain-Werten arbeiten kann und 0 db Gain exakt den 400 ISO entspricht. Interessant ist dabei vor allem, dass dies auch in den anderen Bildprofilen gilt, in denen man auch Einstellungen unter ISO 400 findet.

    Ein kurzer Check bestätigte: ISO 400 entspricht auch im Standard-Profil weiterhin 0dB, während ISO 200 mit -6dB angegeben werden. ISO 200 entspricht also einem Negativ-Gain und somit einer Absenkung unter die Base-ISO, zumindest wenn die angezeigten Zahlen stimmen sollten (wovon wir stark ausgehen). Und das würde wiederum bedeuten, dass man auch in den anderen Profilen für die beste Dynamik immer ISO 400 wählen sollte, selbst wenn ISO 200 vorhanden ist. Und es ist stark anzunehmen, dass dies auch für den Fotobereich zutrifft. Diesen Beweis überlassen wir aber den einschlägigen Foto-Test-Gazetten…
    https://www.slashcam.de/artikel/Test...e-I.html#Bemer
    Kind regards,

    Wolfgang


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    #35
    Senior Member Thomas Smet's Avatar
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    That is because it is the base ISO. Base ISO is not native ISO. Base just means the lowest it can go. You can only go down to ISO400 if you shoot V-log. That is how it was designed and a fact of the camera. It isn't some belief of the internet but a cold hard fact. Those articles are pointing out that V-log does start at ISO400 just like the Sony starts at ISO1600 when shooting log. It isn't an assumption of what is the native ISO but the only way you can shoot log at the lowest allowed ISO level. Some people have assumed the GH4 has a native ISO of 400 because of V-log but that is just a guess. Base just means base.


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