C100: Any difference btw C-LOG w/a WDR LUT and native WDR?

J

jhbass

Member
*Please forgive me if this is a stupid question*

But is there any difference between shooting C-LOG and applying a WDR LUT (AbelCine) in post and just shooting native WDR?

Thanks!
 
C-log has basic ISO 850 (WDR has ISO320) and a different way of exposure at middles than WDR. Also noise levels and high ISO at lowlight are different.
 
In my experience ISO 320 in Wide-DR is slightly cleaner and sharper with less noise in the blacks, but also loses dynamic range in the highlights in addition to occasionally having banding which is not present at ISO 850. As such, I don't see why ISO 320 would be considered the base ISO on Wide-DR while 850 is the base ISO on C-Log.

As for the question, applying the look in post means you're stressing the codec by manipulating the image in post. Any adjustments you make in post to a compressed codec will negatively affect the image with results such as artifacting, banding, noise, etc. If it is just small adjustments the negative affects may not be noticeable. Thus, if you know the look you want (such as Wide-DR) it is generally better to shoot in-camera closest to what you want as opposed to adding the LUT in post. If you want to keep your options open and retain more flexibility in post then you can shoot flatter, at the cost of image degradation from stressing the codec.
 
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I'm yet to encounter a one click LUT that does anything remotely useful. I guess there are scenes and exposure scenarios where it could work, but most of the time they've only butchered my images (crushing/blowing out).

Generally, Canon Log will give you the most flexible image possible out of the Canon 8bit files. That said, some unlit, documentary style scenes might benefit from a steeper curve like the WDR, that adds more contrast to shadows/mids.

Eric Coughlin said:
As for the question, applying the look in post means you're stressing the codec by manipulating the image in post. Any adjustments you make in post to a compressed codec will negatively affect the image with results such as artifacting, banding, noise, etc. If it is just small adjustments the negative affects may not be noticeable.
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You probably didn't mean this the way I read it, but once in post we're not stressing the codec anymore. Any color/luminance manipulation is handled internally in the editor at a much higher bitdepth without compression. DaVinci Resolve, for instance, uses 32bit floating point calculations.

Then again, editing 8bit source material, if you try to separate two luminace values too much, you will get into trouble since there simply isn't any data in the source file. Then it won't help that you are editing in 32bit floating point.
 
Eric Coughlin said:
In my experience ISO 320 in Wide-DR is slightly cleaner and sharper with less noise in the blacks, but also loses dynamic range in the highlights in addition to occasionally having banding which is not present at ISO 850. As such, I don't see why ISO 320 would be considered the base ISO on Wide-DR while 850 is the base ISO on C-Log.

As for the question, applying the look in post means you're stressing the codec by manipulating the image in post. Any adjustments you make in post to a compressed codec will negatively affect the image with results such as artifacting, banding, noise, etc. If it is just small adjustments the negative affects may not be noticeable. Thus, if you know the look you want (such as Wide-DR) it is generally better to shoot in-camera closest to what you want as opposed to adding the LUT in post. If you want to keep your options open and retain more flexibility in post then you can shoot flatter, at the cost of image degradation from stressing the codec.
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I made a lot of tests at day light or at night and there is no need to shoot with wdr and iso 850 at day light scenes.
 
Wouldn't ISO 640 be considered the native ISO since it is 0dB gain? I always thought 0dB gain would naturally be the native ISO. I understand that Canon recommends ISO 850 (+2.5dB gain) as the ISO for C-Log, but I just always assumed that C-Log was fine tuned for that ISO and not that it was "native" ISO.
 
Pave1 said:
I made a lot of tests at day light or at night and there is no need to shoot with wdr and iso 850 at day light scenes.
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With Wide DR at ISOs below 850 on the waveform monitor the highlights show as clipping below 100 IRE, while at ISO 850 it clips at 100 IRE. This seems to me to be an indication that you lose dynamic range in the highlights below ISO 850, which coincides with the Dynamic Range chart for the C100, which says it is for Canon Log, but according to the Waveform monitor looks like it applies to Wide DR as well. So if you're shooting outside and need more range in the highlights, then ISO 850 seems best, while if you have enough range for lower contrast scenes then ISO 320 is good.

Then of course there's also the banding issue at ISOs below 850. It doesn't seem to come up much outdoors, but I've certainly had it come up indoors even under good lighting, such as with a full interview setup shooting at ISO 320 at f/4. Sometimes I'll see banding, switch on an ND, and shoot at ISO 850, and then the banding is gone.
 
Eric - this WDR gamma hasn't 800pct dynamic range as log gamma, so there is no need to use the 850 ISO. The black level of WDR is the same as cine1 has, the middles are a very close to cine1, only highlights are much more compressed then cine1. WDR gamma needs to be a little underexposed in middles, if it is not then "upper middles" are a little desaurated which is not nice on faces.

Basic ISO is 640 (0dB gain) for all gammas (normal3, cine1, WDR) except log gamma. But for less noise you can use ISO340 at sunny days, I have no cilipping of highlights at this case, nice picture. Banding was present on one fine color gradient wiht WDR and log gamma at highlights, cine1 has no problem.

But I will test your scenario, I may be wrong - It is not heavy for me to learn something new .-) .

I like wdr gamma a lot and for little underexposed pictures at middles I usually work with the LCD brightness set from "normal" to "bright" - this is my experience how to get in easy way little underexposed pictures if I have no time for working wih a WF monitor.
A sample of this sort of my quick work is here (wdr gamma) - https://www.youtube.com/watch?v=3OMfoGGk31o
 
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AndreeOnline said:
What do you mean by "native ISO"? Once we have the answer to that, we can probably clear things up.
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What I mean by "Native" ISO/Gain is the native or base sensitivity of the sensor without any amplification or attenuation of the signal. I believe the specific definition of native ISO or gain as used by digital camera manufacturers refers to a measure of the sensors sensitivity necessary to fully saturate the sensor's photosites. My understanding was that RAW data comes off the sensor and then can either be amplified (ISO/Gain increase) or attenuated (ISO/Gain decrease) or be left at the sensitivity level it came off the sensor (which I would call the Native ISO or Gain).

My understanding might be completely off base and if so I would love to know where I'm going wrong in my thinking.
 
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