C100: C-Log Grading Workflow

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wgtwo

Well-known member
What grading workflow do you follow when working with C-Log footage?

Never really used it before, and now that I have my Ninja Blade, I've decided to give it a shot. Did some tests (on DNxHD 220x), pushing contrast a lot. First, I tried just doing it by eye, using Colorista II and Filmconvert; here's the final image, very aggressive: http://i.imgur.com/u8rN0OJ.jpg and waveform, doesn't look too bad: http://i.imgur.com/VZMn9aO.jpg Then, however, I started fresh and tried applying LUTs from AbelCine. The Canon one (CxxxLog10toWideDR_Full.cube) looked awful on the waveform, huge banding gaps. Tried a different one, I believe made by AbelCine themselves (ABNorm_CxxxLog10toWideDR_Full.cube), and it looked better, though still quite shakey: http://i.imgur.com/EvlRK8r.jpg Then I tried doing a quick grade (placing a Fast Colour Corrector on TOP of the LUT) and it smoothed out a fair bit, but still didn't look at solid as the original non-LUT grade: http://i.imgur.com/sgTZfri.jpg

With all of these, I found myself pushing mid tones down a fair bit, though that may have been down to bad exposure and/or the scene itself.

Still not really clear on correct usage of C-Log vs WDR (everyone seems to have their own opinion and is very vocal about it). Should I actually, say, use C-Log for general sunlit exterior shots and WDR for windowless interiors, or would it be better to stick with one for consistency? How real is the risk of the C-Log gamma curve overwhelming the C100 8-bit-ness, in your experience?
 
Here is a bit of my process.

Starting Point:
cc_1.jpg


Y Waveform clearly has room to be expanded. So I'll adjust the Setup & Gain, Contrast & Saturation to make the image 'pop' a lot more. You can see the adjustment I made here -> Y Waveform is clipping very slightly on the highs and lows, but I liked the look I got.

cc_2.jpg


Now I'll jump into Hue Offsets and sample the darkest areas, and lightest areas. I did a very slight adjustment so I can get black as close to 16,16,16 as possible (sampled from the lower right chest site of suit), and the whites as close to 256,256,256 as possible (sampled from left collar here). Values I got from sampling are on the right side (20,13,23 - 250,251,253). Technically my blacks are too high for Red and Blue, and white is pretty darn close.
cc_3.jpg

The starting point to finished image is obviously a lot different. I could have graded it more to have a visual 'style', but for this particular one, natural seemed to work best. I wouldn't have been able to retain the pattern in the shirt in the collar and the detail lower in the suit had I shot WideDR or EOS Standard.
 
Are those gaps in the RGB Parade alright? That's what I was talking about when I applied my Canon LUT - it's true, you can't really see it in the image, but I read that it contributes a lot to the 'video look'; minutely rough gradation that takes away from the overall image.

I never generally got much of that when working with WDR, for obvious reasons.
 
The tonality in Canon Log lives below IRE60. Generally, you probably don't want to shoot footage where you need to pull back the mid tones in post. If you do, you are likely to get flatish footage that will grade poorly.

I find myself pushing my mids slightly up, but only as a consequense of dragging the black point (and with it some mids) down where it belongs. In essence, try to nail the mids in exposure.

I think the banding you see in the waveform is software-rendering related. I don't get that in FCPX. It's most likely a waveform refresh thing that is unrelated to the actual image?
 
Looks to be exposed more or less right, then: http://i.imgur.com/tk63Tls.jpg Probably just personal grading taste. Anyway, beside the point!

Don't think it's software related, seeing as it's happening in chappelldigital's Media Composer as well. Though I'm not sure why it's happening there as it only really happens to me if I delog via LUTs.

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Huh, wait. So, with just the LUT, they look like this: http://i.imgur.com/aB2shsQ.jpg, but if I apply a Fast Colour Corrector, even if it does not visibly alter the image at all, this happens: http://i.imgur.com/TaBmA9u.jpg

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Okay, no, looks fine in Speedgrade, so you're probably right. Are there any real downsides to shooting C-Log on a Ninja, then?
 
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