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ProRes & cinemaDNG
2299 6 2018-1-17
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Alex Dawson
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Hi,
i just activated my X7 on my inspire 2 drone and have been planying inside (due to a snowstorm outside)
I have never shot ProRes or cinemaDNG before but have 15 years experince from RAW stills and how it works.

What I dont understand is when shooting in D-log and cinemaDNG the output looks mush harder (contrasty)
than if I use similar settings on ProRes. I was expexting a realy flat RAW file from cinemaDNG but its not?

Is there a setting I have missed?

I am importing my videos to Davinci Resolve 14 and for cinemaDNG i use Rec.709 and Gamma 2.6 i RAW


cinemaDNG

cinemaDNG

ProRes

ProRes
2018-1-17
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GHeo
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I think you have applied the rec 709 lut to the image which gives you more of a "baked in" look, try removing rec 709 and it should be much flatter i think. Not totally sure cause i'm just getting into Devinchi, but it might be worth a try
2018-1-17
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Barry Goyette
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DJI has unfortunately confused the issue by allowing you to record RAW in D-Log. The problem is that it's not really what's happening. RAW is always RAW...and whatever preview you are seeing in ACR, or Resolve ETC is the result of a metadata tag that is telling your computer how to render a preview of the image (RAW images are horrible to look at without a profile attached). D-Log is a gamma applied during Debayering and conversion to ProRes and H264(sort of). Linear Gamma (Rec.709) is the same and is normally how Raw images are viewed. The main purpose of a LOG Gamma is to allow for RAW-like exposure adjustment of (generally compressed) non-RAW images, as the distribution of code values is more even throughout the tonal range than linear encoding, and thus can sort of do an end-run around the problem of adjusting lower bit (10) footage. RAW images generally exist in a higher bit level (12), and thus don't require this redistribution of code values for simple exposure changes in a RAW converter like ACR or Resolve.

It's not uncommon to think that the "flat" LOG rendering means that the file has more dynamic range, but that's not the case, especially when it comes to comparing to a RAW File. In RAW, there is a huge amount of DR being hidden by the Linear Gamma preview, and all you have to do to expose it is to start adjusting various sliders (exposure, highlight, shadow, etc). If I'm being opaque here, lets just say that there is no real benefit to handling RAW files in LOG, and it's not really a standard way of dealing with it. Linear is the generally considered the "correct" way to work with raw, if there is such a thing.

Now...DJI has recently made available a "reverse" LUT, that will convert RAW CDNG to LOG. I haven't the faintest reason why. But if it's what you want, go to the X7 or X5s Download pages and grab the "Linear to D-Log" LUT. It works in Resolve and Premiere.
2018-1-17
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Alex Dawson
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Barry Goyette Posted at 2018-1-17 12:30
DJI has unfortunately confused the issue by allowing you to record RAW in D-Log. The problem is that it's not really what's happening. RAW is always RAW...and whatever preview you are seeing in ACR, or Resolve ETC is the result of a metadata tag that is telling your computer how to render a preview of the image (RAW images are horrible to look at without a profile attached). D-Log is a gamma applied during Debayering and conversion to ProRes and H264(sort of). Linear Gamma (Rec.709) is the same and is normally how Raw images are viewed. The main purpose of a LOG Gamma is to allow for RAW-like exposure adjustment of (generally compressed) non-RAW images, as the distribution of code values is more even throughout the tonal range than linear encoding, and thus can sort of do an end-run around the problem of adjusting lower bit (10) footage. RAW images generally exist in a higher bit level (12), and thus don't require this redistribution of code values for simple exposure changes in a RAW converter like ACR or Resolve.

It's not uncommon to think that the "flat" LOG rendering means that the file has more dynamic range, but that's not the case, especially when it comes to comparing to a RAW File. In RAW, there is a huge amount of DR being hidden by the Linear Gamma preview, and all you have to do to expose it is to start adjusting various sliders (exposure, highlight, shadow, etc). If I'm being opaque here, lets just say that there is no real benefit to handling RAW files in LOG, and it's not really a standard way of dealing with it. Linear is the generally considered the "correct" way to work with raw, if there is such a thing.

Thank you Berry! A lot of information and yes DJI has made it more confusing. I will check their DNG to log I downloaded it earlier...

Thanks again // Alex
2018-1-17
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Alex Dawson
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Alex Dawson Posted at 2018-1-17 12:43
Thank you Berry! A lot of information and yes DJI has made it more confusing. I will check their DNG to log I downloaded it earlier...

Thanks again // Alex

So since my intention is to shoot in RAW there is no point in using of EI mode for me and limit myself to iso 1600 then? Is that correctly assumed that EI mode is only really for H.264/265 and ProRes?


// Alex
2018-1-17
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Barry Goyette
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Alex Dawson Posted at 2018-1-17 13:06
So since my intention is to shoot in RAW there is no point in using of EI mode for me and limit myself to iso 1600 then? Is that correctly assumed that EI mode is only really for H.264/265 and ProRes?

The RAW files produced by EI mode, and Normal Mode are identical, other than possibly a difference in preview profile.

EI mode does not limit you to shooting at 1600. All ISO's are available. Native ISO is 100, other ISO's are gained from that, and there doesn't appear to be any difference in DR with the various ISO's. (1600 does produce an additional 1/2 stop of DR, but it is a really noisy 1/2 stop that I don't think really counts "-).

EI mode currently is only recommended for ProRes. The H264 version is a mess. When shooting H264, it is best to use normal mode. D-cinelike will give you a wideDR look.
2018-1-18
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Alex Dawson
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Thank you Barry! Good to get that information confirmed

Kind regards // Alex
2018-1-18
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