C100: shooting C100 in C-log

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nickbeef

Active member
I recently shot 2 projects in C-log, and after grading I'm not sure if I totally prefer it over shooting in WideDR with less color correction. I'm thinking maybe it's because the highly compressed codec, there might just not be enough information to stretch the image back out with out without losing the image. When I then compress it again for delivery, I'm feeling like I'm losing even more of the image. Would shooting to a Samari Blade or other external recorder improve this? Is an external recorder (with a higher color space codec) necessary for shooting C-log? Especially when the workflow is LUT > correction > look?

Or maybe it's because I'm not properly exposing for C-Log? I try to keep the image fairly underexposed, because the LUT's I use end up overexposing if I don't. Is this the right way to shoot? I haven't been able to come across a good explanation for how to expose for C-log on a C-100.

Also, maybe it has something to do with the LUT's I'm using? I think I got them from AbleCine, but is there a more "official" LUT out there, or at least a highly recommended one?
 
I looked a lot of stuff up before my first (and so far only) c-log shoot, did some tests. I believe the whites are crazy crushed down in c log and the blacks are pushed way up. . .like 90% white is equivalent to 63% in c-log. So with your waveform on, know that anything over 63% will be blown out. Something like that, if not exactly right. There are various articles and threads if you Google search that should give you better info.
 
Josh, thanks for the info, but believe me I've searched for articles on this topic, searched youtube, and this board. Could you recommend any articles? I'm not sure what I'm missing.
 
Perhaps first: if you're looking to arrive at a 'look' that is similar in contrast to Rec 709, then you should probably use a picture profile that is closer to that to begin with. No need to shoot flat, then push and pull to much with 8bit long GOP.

When analysing your scene you should make a distinction between reflected light and direct light. Example:

  • A white shirt or a bride's dress that is bombed by sunlight is reflected light—albeit very bright.
  • Shooting an office scene out of a window, you can regard the window as a "direct light source".


It is extremely important that reflected light isn't allowed to climb up too high on a waveform. I'd say below 70 or so for bright surfaces.
But, depending on your scene you might very well have someone close to a window to get that nice fall-off from a huge "light source", and in this case you'd naturally expose for the window—comfortably fitting its intensity into available DR— and let that light drape the person standing next to it.
If you however shoot someone inside a room and there is a window in the background or further away, I wouldn't personally worry about this window blowing out.

There is a physical reality to how light works, how its intensity falls of according to inverse square law and how much DR your camera offers. Sometimes you compromise and simply let the light fall where it may, other times you make an incompatible scene compatible by directing or filtering light.

One mistake I think people make is to think that "log shouldn't clip", and they make way to large compromises to fit a bright direct light (can be a window) thereby pushing the rest of the image into the mud.

Don't start out using LUTs. Just lower the blacks and adjust saturation to your liking. Maybe add a wee bit of contrast to the lows-mids. See how that looks. Many LUTs try to make a Log--->Rec709 conversion and that's just disaster.
 
I've been shooting the C100 for two years now and have never used C-Log. I have a Ninja Blade, which might help it out a little but the comments the OP made are mostly what I hear about using log on the C100. With 8-bit, just not worth it. I use Wide DR or a few custom CPs I developed and tested and my clients like the look. C-Log, if you are handing footage off to clients who don't know what a LUT even is, much less how to use one, is a risky proposition. Most of my clients are the publicity and home entertainment departments at the studios and they like a baked-in, high-contrast, punchy color look. So that's what I give them. I have shot some corporate pieces recently for LA Metro that involved people of color on blown out, way too bright concrete train platforms with little light control possible (walk and talks, so even though I had a grip/gaffer, we didn't have the gear or time to properly flag off the path the talent walked) so having an extra stop or two of latitude would have been helpful. As it was, I had to do what Andree suggests and just expose for talent and live with the blown out BGs. Killed me but client was happy and the circumstances didn't warrant a better solution.

I am much more interested in working with log profiles with the C300 MKII, I may really delve into it but with the C100, probably not the best way for me to work.
 
Not using Log is of course a fine choice if the aesthetic doesn't fit. Nonetheless here is an example of what I mean regarding using a LUT.

Log
Log.jpg


Log | Black and gamma adjust + saturation
LogAdjust.jpg


Log | One of those Rec.709 LUTs made for Canon Log
LogRec.jpg
 
I shoot WideDR on any project where I know I'll simply be handing off the footage to someone else for post. But if I'm doing the post work myself, I always shoot C-log out to my Ninja Blade. I tried using a LUT one time for my color correction. Never again. I use MB Looks for most of my post work, and I find that making minor adjustments within my three-way color corrector tool usually gets me right where I need to be, as long as I had proper exposure during production. When I don't get proper exposure and I have to really mess with the my highlights or shadows and I find I'm running into a little bit of noise, I can usually get it cleaned up with MB Denoiser 2.
 
I just shot a 1 minute horror film using c-log. I generally shoot with wide dr, but I opted for c-log because I knew I was gonna crush the blacks in post and I wanted to preserve details in the highlights. That was my first time shooting a project using c-log, and I think that's what it'll be using from my personal projects from now on. BUT, I really do like wide dr (a lot) and will continue to use it for client projects! Here's a link to that 1 minute horror that I shot using c-log. https://vimeo.com/180629205
 
After years of using some flavor of Wide DR, I've become recent convert to C-log. Like Andree says, you don't NEED to use a LUT, but it can be helpful, especially as you're starting out with C-log.

My workflow with a LUT in Premiere Pro goes like this: I place an adjustment layer above all my C-log clips, and apply the Lumetri Color effect to that adjustment layer. In Lumetri, I load one of AbelCine's conversion of the official Canon LUT (either clog-to-widedr or clog-to-rec709).

But here's the trick: I also apply a color correction effect on the actual clip too, and I correct the blacks, mids and highlights before the LUT does it's job. So for example, you shoot a clip and drop the LUT on. You like where the LUT puts the skin tones, but now the sky is totally blow out. So you apply correction before the LUT does it's job, and you bring the highlights back down. Here's a recent example from one of my own projects: https://postimg.org/image/6m9obedbl/
 
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drummondb said:
Like Andree says, you NEED to use a LUT, but it can be helpful, especially as you're starting out with C-log.
Click to expand...

=)

I hope you meant to put a 'don't' in there somewhere, or I seriously need to work on my communication skills...

But like you say, you can use a LUT and scale it back by reducing the effect (depending on software). One example is to use a film conversion LUT to start shifting certain hues in a new direction, but you might not want to go 'all in'.

I personally also feel that you should start learning WIHTOUT LUT to better get a feel for what the camera captures and how the image reacts when you start to pull it. Doing manual work takes you from A via B-C-D-E to F, but a LUT might get to from A to F in one fell swoop and you might not realise what happened.
 
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Sorry to resurrect an old thread. I'm a Black Magic camera shooter/grader buying a C100/2 for ease of use. I've noticed a few comments about using LUTs on log footage and, since I'm searching through old threads, thought others might too.

As suggested above, a LUT isn't a one-click 'look'. It takes the image from A to B by a fixed amount and it doesn't know how you exposed your image, how well you white balanced, etc. Most LUTs seem to be made with very low contrast images in mind, so they blow out the highlights of many shots. I'd recommend people download Davinci Resolve (free) and experiment with two nodes, the second containing the LUT and the first used for bringing down the highlights, boosting the shadows (perhaps) and adjusting the white balance as needed.

I've used this approach on a hired c100/2 and, although there is much less to play with when compared to files from a BM camera, there is still enough information in most shots to get a nice image.
 
Ben Drissa said:
Sorry to resurrect an old thread. I'm a Black Magic camera shooter/grader buying a C100/2 for ease of use. I've noticed a few comments about using LUTs on log footage and, since I'm searching through old threads, thought others might too.

As suggested above, a LUT isn't a one-click 'look'. It takes the image from A to B by a fixed amount and it doesn't know how you exposed your image, how well you white balanced, etc. Most LUTs seem to be made with very low contrast images in mind, so they blow out the highlights of many shots. I'd recommend people download Davinci Resolve (free) and experiment with two nodes, the second containing the LUT and the first used for bringing down the highlights, boosting the shadows (perhaps) and adjusting the white balance as needed.

I've used this approach on a hired c100/2 and, although there is much less to play with when compared to files from a BM camera, there is still enough information in most shots to get a nice image.
Click to expand...

Ive been playing around everyday shooting some practice footage, and then editing and applying luts in Color Finale. Always shot wide DR before so this is new to me. I understand the difference now between a rec.709 LUT and a LOG LUT. Although from what I'm learning either one of these LUTs isn't written in stone. You can apply a LOG-LUT to C-Log footage, and in some cases looks better than a REC. 709 and vice versa.

Yesterday I shot some practice footage, used a grey card, and nailed the exposure (at least I think I did.... ha!) and applied a rec.709 LUT and it still looked washed out. Then I tried a a LOG LUT to the C-Log footage and it looked much better. Then started tweaking it. Grading with wide DR I would bring the blacks right down to zero, however most all the LUTs bring the black right about 7.5 above zero. Is this the way it should be for a LUT? If I go back and adjust a LUT and bring the blacks down to zero they get horribly crushed.

Also, one thing Im wondering is how far one can stretch the grading using AVCHD without destroying the image? Adjusting the expose a little, applying a LUT, etc. how much is too much? Before I always used a Ninja Blade and never worried too much about it. Now since I got a new C100 MKII specifically for using on a Helix without the Ninja, this has become a concern for me.

Also, I've been comparing just color correcting and grading to get the image close to the look of some LUTs, and sometimes actually prefer what I've come up with more than the LUT.
 
Hi Michael. You're right that the files from a C100 (even using an external recorder) don't allow much room for grading.

My point was that a LUT isn't really a 'correction' tool. It can't analyse your image, decide what will look best, then respond accordingly. It takes pixels and moves them, by a fixed amount, somewhere else.

Not a quick solution, but I'd suggest downloading Davinci Resolve, for free, and watching a couple of tutorials. You can adjust an image to your liking, then save the adjustments as a 3D LUT. You'll then have your own custom LUT, or maybe a few for different kinds of shot, which I imagine could be imported into Color Finale.
 
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