Thread: GH5 V LOG Proper Exposure
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04-17-2017 08:06 AM
I do not see any difference in the advise for v log l and s log2/3 really. The general rule is to use the native iso, and apply white or gray cards to adjust the a waveform or zebra. The points of 50% and 90% are defined in the white papers and wellknown. If one wishes to reduce noise a typical approach is to reduce the ISO and stick to these points, if necessary. That is not different for the GH4 and the Shogun, or not different for my FS7 - and why should it be different for the GH5 beside the point that we have now an internal waveform monitor and internal 10bit recording up to UHD 30p/DCI 4K 24p?Kind regards,
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- Jan 2006
- Nashville, TN
04-17-2017 12:18 PM
- Join Date
- Sep 2003
What's different about VLOG-L vs. other logs is when we get to the "common advice" nonsense that floats around the web that "you should always overexpose log by a stop or two." That's the part I'm referring to. Whereas people have been able to get away with doing that with other logs that have symmetrical curves (-6/+6 around middle gray) it is utterly terrible advice for VLOG-L (which is asymmetrical, -8/+4). Overexposing VLOG-L by 2 stops would result in a curve of -10/+2! Your skin tone levels would be practically the same level as white.
It's just bad advice and needs to be stamped out.
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04-18-2017 11:09 AM
Agreed. Any arbitrary "overexpose by X amount of stops" is just silly and really just shows the repeater's lack of knowledge about how digital sensors work.
Whether people like it or not, there is one surefire way to maximise exposure and dynamic range in any digital camera - Expose To The Right.
Do that and you will ALWAYS keep your highlights intact, and give your sensor the most latitude, as long as you white balance properly first. Then your shadow detail will be as clean as possible and you will see as deep into the shadows as possible, to the limit of the sensor.
I shoot like this 100% of the time with accurate, repeatable results. Yes, this method requires balancing the shots down in post to match what you saw on set. But if you are serious about image quality, you are doing this already. The result is clean, deep blacks with lots of shadow detail, no clipped highlights and a beautiful, filmic image.
Why shoot any other way, unless it's for instant handoff, and even then, it still helps to have your zebras set to ETTR clipping just so you know you haven't clipped your image.
04-18-2017 11:31 AM
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.
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04-19-2017 03:01 AM
But beside that we have to be very specific, I think. According to Panasonic the native ISO for the GH4 is 800 (and the same for the GH5 I think). The dynamic range should have a maximum of the 12 stops with ISO 800. For the log shooting with FS7 a typical advice is to reduce the actual ISO below the native ISO - what reduces both noise but also the dynamic range. For the FS7 it is less important maybe, compared to the GH4/GH5 - due to the higher number of stops (14) but also the more symmetrical log curves both in slog2/3. So to adjust ISO in the GH4/5 for example from 800 to 400 is possible, but will harm the dynamic range. Because what will we do with our beloved white and gray cards (I use the same as shown in the link to Alisters page) - we will still stick to expose to the 42 IRE or 61 IRE. Means, that we will overexpose by 1 stop if we follow that approach. And then we reduce the footage again in the postpro by this 1 stop. So this is one possible form of ETTR - but limited in this example to 1 stop and not exposing as high as possible (until your footage reaches IRE81 and start to clip).
04-19-2017 05:51 AM"If at first you don't succeed, try, try again. Then quit. There's no use being a damn fool about it." - W.C. Fields
04-19-2017 06:05 AM
04-19-2017 08:46 AM
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.Kind regards,