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    #21
    Senior Member Thomas Smet's Avatar
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    Quote Originally Posted by wschmid View Post
    800 is what one find in the net - but you are right: I have not seen that published by Panasonic. By the way, that is something that is not great too. We have the same situation with Sonys FS7 - where a lot of people talk about a native ISO of 2000 in the CINE EI mode, but a lot of usere report that this is wrong.

    It would be great if the industry would publish those figures really - since there the dynamic range should achive a maximum.
    I think there have been plenty of tests like the one at DXOMARK to indicate the myth of dynamic range is better at a higher ISO is just not true. That may be true for some cinema cameras but it doesn't seem to really ever be true in the DSLR world.


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    #22
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    Quote Originally Posted by wschmid View Post
    800 is what one find in the net - but you are right: I have not seen that published by Panasonic. By the way, that is something that is not great too. We have the same situation with Sonys FS7 - where a lot of people talk about a native ISO of 2000 in the CINE EI mode, but a lot of usere report that this is wrong.

    It would be great if the industry would publish those figures really - since there the dynamic range should achive a maximum.
    There is no such thing as "native ISO" for digital cameras, ISO is just an arbitrary luminance gain factor. Camera manufacturers manipulate ISO behind the scenes to produce consistent exposure levels among camera models set to the same lens aperture and shutter speed. Until recently, cameras used Rec 709 built-in profiles and ISO was fairly well standardized. But the ISO of a LOG tone curve is not directly comparable to Rec 709 ISO, it depends on where the midpoint of the LOG scale is positioned. With the GH4, Panasonic manipulated the V-log L tone curve to make its numerical ISO about twice the ISO of the built-in Rec 709 tone curves.


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    #23
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    I'm generally a fan of ETTR, and it is a great way to go if you have no reference point, but it can definitely be abused and misunderstood to the point it severely degrades PQ.

    I see this most often when a shooter tries to protect too much – usually a sky that is so bright that saving it causes the actual subject matter to be recorded in the shadows. Because just about every part of the image pipeline is designed to sacrifice the shadows, when you lift them you're left with a noisy, muddy, compressed footage.

    It's a more nuanced technique to explain, but I tend to use a hybrid approach: Properly expose the subject (w color chart if I can, skin tone if I can't) and then adjust a stop or two to try to protect highlights if I can.


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    #24
    Senior Member visceralpsyche's Avatar
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    Quote Originally Posted by wschmid View Post
    But how exatly do you implement the "expose to the right"? One way would be to increase the luminance compared to the approach above, using for example the new waveform monitor in the GH5 (or the Shogun together with a GH4). You can increase the luminance until the signal start to clip at the 81%. No idea where your are compared to the approach where you use a grey/white card - but you use the maximum of the luminance range that is available. So what approach do you follow in detail?
    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 As always, you need to be judicious. No point in ETTRing to keep street lights from clipping - you'd have no image left. But the zebras show you precisely what is clipping, so you can make a decision on whether you want to clip it or not, rather than guessing by some arbitrary overexposure value with the zebras set to skin tone or something.

    More info about how to ETTR here.

    Cheers,

    Paul
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    Quote Originally Posted by Bern Caughey View Post
    Barry speaks to ETTR in the White Paper, & it's worth a read.

    As someone who hands off most their footage I'm not a fan of ETTR as it creates at lot of work for the DIT, &/or post. For consistent exposure, especially skin, I use either False Color, or Zebras with a 18% Grey/90% White card.

    http://www.xdcam-user.com/2014/07/la...e-card-review/
    Bern, I'm interested in finding out a bit more about your approach when exposing for skin. Obviously, there is a range of skin out there, but when using false color or zebras, what are you generally shooting for? How are you doing this when shooting in a rec709 profile on say the GH5, and how do you approach this when shooting in Vlog on the GH5?

    ETTR is simple enough and has its advantage, but I too have to hand off footage a lot of the time, but some clients ask for the flattest (log-like) footage, while others want a ready to edit look. I'd love to hear about your approach for both when using false color or zebras.

    Part of my question also stems from having finally gotten more reliable exposure tools to work with (smallhd monitor and the GH5's new exposure tools).

    Thanks in advance!

    O


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    So is vlog-l better on gh5. Tested vlog-l on gh4 and it didntn give me better highlight laditude. Would be great if gh5 could give 1 stop better highlight range


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    #27
    Senior Member wschmid's Avatar
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    Quote Originally Posted by Thomas Smet View Post
    I think there have been plenty of tests like the one at DXOMARK to indicate the myth of dynamic range is better at a higher ISO is just not true. That may be true for some cinema cameras but it doesn't seem to really ever be true in the DSLR world.
    Nobody said that the dynamic range will be better at a higher ISO?
    Kind regards,

    Wolfgang


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    #28
    Senior Member wschmid's Avatar
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    Quote Originally Posted by Lpowell View Post
    There is no such thing as "native ISO" for digital cameras, ISO is just an arbitrary luminance gain factor. Camera manufacturers manipulate ISO behind the scenes to produce consistent exposure levels among camera models set to the same lens aperture and shutter speed. Until recently, cameras used Rec 709 built-in profiles and ISO was fairly well standardized. But the ISO of a LOG tone curve is not directly comparable to Rec 709 ISO, it depends on where the midpoint of the LOG scale is positioned. With the GH4, Panasonic manipulated the V-log L tone curve to make its numerical ISO about twice the ISO of the built-in Rec 709 tone curves.
    The native or generic ISO has always be defined in relation to the minimum noise level - was at least my understanding. True that there seems to exist different numbers for log or rec709 curves - but that does not mean that we will not have an iso figure where the noise signal ratio should become a minimum.

    Beside those more theoretical aspects I would really like to know how you expose v log l if you assume that the iso
    is not important. Because if that would be true, the the use of gray cards and 50% reflection points become less important. Then you adjust with either iso or exposure the luminance, and as long as you have enough light or do not go into clipping everything is fine.

    I want just to point out that ETTR is the direct consequense of this approach. But expose to a white or gray card follows another approach what is not in line with ETTR really.
    Kind regards,

    Wolfgang


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    #29
    Senior Member wschmid's Avatar
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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 As always, you need to be judicious. No point in ETTRing to keep street lights from clipping - you'd have no image left. But the zebras show you precisely what is clipping, so you can make a decision on whether you want to clip it or not, rather than guessing by some arbitrary overexposure value with the zebras set to skin tone or something.

    More info about how to ETTR here.

    Cheers,

    Paul
    Right, beside the suggested use if the zebra I prefer to use the waveform monitor for that, since that tool gives me more information then the zebra. Quite clear that lamps in a night setting will clip since your dynamic range is limited anyway.

    So far so good - and my impression is that this is a very good way to utilize the dynamic range of the camera in the best possible way, since you bring it in line with the dynamic range of your szene. The only questionmark that I see is that you can end up with a wrong luminance in some cases (for example, a person in a darker room in front of a bright window may end up too dark). That are cases where the use of gray cards can be a good idea - to get the exposure of this person right.

    But that is fine.
    Kind regards,

    Wolfgang


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    Quote Originally Posted by ozmorphasis View Post
    Bern, I'm interested in finding out a bit more about your approach when exposing for skin. Obviously, there is a range of skin out there, but when using false color or zebras, what are you generally shooting for? How are you doing this when shooting in a rec709 profile on say the GH5, and how do you approach this when shooting in Vlog on the GH5?

    ETTR is simple enough and has its advantage, but I too have to hand off footage a lot of the time, but some clients ask for the flattest (log-like) footage, while others want a ready to edit look. I'd love to hear about your approach for both when using false color or zebras.

    Part of my question also stems from having finally gotten more reliable exposure tools to work with (smallhd monitor and the GH5's new exposure tools).

    Thanks in advance!

    O
    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.


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