Test shoot with light meter and c-log

[Bob Drummond]

Hello, friends. Posted this on the other board, but I figured I'd share here too.

In my never ending quest to get better at C-log, I bought a light meter, and ran some tests. Let me know what you think:

C100 c-log and Sekonic L-308DC light meter test on Vimeo

[Charles Papert]

My question would be: did you find the light meter any more useful than using the waveform in this scenario? I wouldn't think so. If you know where you like to peg the skin tones on the WF, there they are and you didn't need a meter to tell you that.

Where a light meter comes in handy at this stage of the game is when you don't have a camera fired up. The only time I use them on set now (after years of using them with film) is when we need to record the output of a given light source, if for instance I need to recreate a lighting setup later on, in a green screen environment etc. When it comes to exposure, I use a combination of waveform, RGB parade and sometimes false color and that gives me everything necessary for standard shooting.

[Rob Katz]

bob and charles-

for those of us not able to have a waveform monitor on set, can you share your thoughts on the often available alternatives: false color and histograms?

i look forward to any insights you care to share.

be well.

rob
smalltalk.productions

[Charles Papert]

Hi Rob:

I don't use histograms--there was that era with the DSLR's in 2010'ish where that entered into my realm by necessity but the last time one came up on a monitor, I was sort of thrown as I had forgotten how to use them! I think histograms are useful for run-and-gun to ensure you are in a ballpark exposure. I think of histogram as a broad stroke for an overall frame--easy to understand if it's a normal contrast scene like a day exterior or well lit interior where the bell curve shape appears, but takes more thought in high contrast to know where the skin tones are falling. In that instance, ETTR makes sense to keep the highlights from clipping, but not a great way to judge individual elements in a frame.

False color is an interesting tool. What I don't like about it is that it works fine for certain scenarios like interviews where the flesh tones tend to be pegged at a similar level, so you can land the appropriate false color on faces and feel confident. But for narrative work like I do, I constantly place faces at different exposure levels depending on the scene. How I use it is to match between multiple cameras pointed at the same subject: I feed a quad split into the monitor and can instantly see if the tones match up and can fine tune iris as needed.

In terms of other types of scopes, this was once an expensive proposition but there are many great options available now. They are built into many (relatively) affordable monitors such as the Small HD's. I use Scopebox software ($99) along with the Blackmagic Ultrastudio Mini Recorder ($145) and have a fully customizable suite of scopes at my disposal. I have a Mac Mini and 20" monitor in my cart setup, but it works fine with a laptop as all of the windows are resizeable. I keep the waveform, RGB display and vectorscope up at all times. I use the latter two when tuning white balance and looking for particular color tones in the shot, matching cameras and light sources, when gelling fixtures to match existing lighting, for instance.

Another great feature of Scopebox is that you can use it as a still or video recorder. It's useful if you need to examine a clip in detail, as you can open in Quicktime and do a frame-by-frame without having to remove the card from the camera and download. That's great for stunts or critical action. The still frame feature is a powerful reference tool; I take grabs of every setup which has proved invaluable over the length of a long project.

Again, I spent many years of my career judging exposure with a light meter. I just find that I using my various methods, I can do the job better and easier. I had a conversation with the colorist on my recent show who had graded both mine and another DP's work in the same environments (the other DP relying on his meter for exposures). The colorist said that my footage was more consistent from shot to shot, he had to do less balancing within a scene.

[Bob Drummond]

Originally Posted by Charles Papert

My question would be: did you find the light meter any more useful than using the waveform in this scenario? I wouldn't think so. If you know where you like to peg the skin tones on the WF, there they are and you didn't need a meter to tell you that...

My problem is, I don't know where I actually want my skin tones while shooting C-log. And this is coming from a guy who has analyzed shots from Barry Lyndon using a waveform. (In Barry Lyndon, skin tones seem to peak around 60 IRE, and white clothing around 90, if anyone cares...)

Charles, I know you say you place your skin tones at different places based on the needs of the scene. But do you have any guidelines you'd be willing to share as to where you generally place skin on the waveform if you're shooting Canon log?

ETA: Looking at my own tests, I'd say having caucasian skin peak around 50 IRE on the waveform in Canon log would be a decent rule of thumb.

[Charles Papert]

Hi Bob:

I have only shot a couple of times with the Canons and it's been a couple of years, so I don't have any specific advice for you, I'm afraid. I don't judge exposure primarily from log myself, I like to be able to monitor it as an option to check for what is being held in highlights, but I will more typically judge exposure from a lutted image. Exception would be if the lut is significantly shifted from a 709-esque luminance range, where it might be a bit deceiving and I need to refer back to 709 or the log image to make sure.

Interesting idea about using a classic film as a reference on a waveform. As an example of how tough it is to give a single answer about where to expose skin tones, think about Gordon Willis' brilliant work, where he would plunge actors into various forms of darkness sometimes to a fault (imagine studio execs wringing their hands that their expensive movie stars couldn't be seen)!