C300: looking for the right IRE level for skin tones in C-Log on the C300 and 1DC…sample

N

Nicholas Natteau

Veteran
Very interested to know what IRE level the rest of you like to have skin tones at when shooting in C-Log. I understand that there's no magic number, that it might be down to preference. But is there a rule of thumb? For example…make sure skin tones are between 50-60% IRE in C-Log?

Please see my 2 minute test footage shot with my Canon C300: https://vimeo.com/73507450
Edited in Premiere Pro CC with Fast Color Corrector applied and Film Convert added.
Film Color set to 50%, Film Grain 45%

Please tell me how well or badly I exposed the skin tone? Am I in the ball park?
On my C300's waveform display, I think my skin tone was at 55% IRE.

Thanks for the feedback.
 
Last edited:
When shooting with a log gamma, caucasion skin tones are generally best at 32-38 IRE. The waveform monitor in the C300 is showing you a graph of the log footage, not the corrected "view assist" preview. Exposing skin at 55 IRE in log would generally be considered overexposed and you'll lose highlight headroom.
 
Thanks for replying cowpunk52. Wow, I would have thought 32-38 IRE would be too low. That's good to know. I'll try more tests at that IRE setting. Thanks again.
 
cowpunk52 said:
When shooting with a log gamma, caucasion skin tones are generally best at 32-38 IRE. The waveform monitor in the C300 is showing you a graph of the log footage, not the corrected "view assist" preview. Exposing skin at 55 IRE in log would generally be considered overexposed and you'll lose highlight headroom.
Click to expand...


Curious if people are still exposing skin at 32-38? I just got back from Shane's illumination experience and listened to him say he exposed that in Need for Speed and it was way under, so he does 55-63% now? That sorta seems high to me in C-LOG.
 
I have personally never felt that is has to be a numbers game. The mark I eyeball has served me well, but there are caveats.

Canon's recommended IRE levels will be on the dark side for sure and I've shot quite a bit of footage that was intentionally over exposed compared to that standard. You just have to be aware of how the Canon Log-profile curve (how it distributes its light values) looks. It has a very smooth roll off that starts pretty early—I think this strongly contributes to the 'natural' look. But as you get into the roll off the image will flatten out and you will lose some tonality that might be desirable in skin.

I am sure you have seen some footage with plasticky looking people? This is a result of people misusing log profiles by exposing to high (spreading the butter too thin). Technicolor's CineStyle comes to mind from back in the early days.

Some might also look at Arri or Sony log footage and their sometimes VERY flat profiles, and try to mimic this when shooting Canon Log in less demading scenes: the scene has limited dynamic range so you try to "expose to the right" to improve signal to noise. You then get a washed out, loggy looking scene, that you want to grade in post. But… the thing is that most log profiles were developed for 10 bits or up. In 10 bit you have many more light values to play with and you can afford to be flat. The same cannot be said about 8 bit. Canon knows this and tried to maximise the 8 bit potential when they developed Canon Log. You need to shoot Canon Log closer to your target look than you would a high bit depth, low compression profile/codec combination.

It is this last part, shooting closer to the desired result that has me over exposing at times when I don't need to reserve quite as much roll off for highlights. In this scenario we can improve signal-to-noise by going "lighter".

I'd listen to Shane as I feel he as done quite a bit of testing, but I would also be surprised if he always lands his skin tones as high as IRE 55+
 
Andree - Thanks for your time and information, much appreciated.

AndreeOnline said:
I have personally never felt that is has to be a numbers game. The mark I eyeball has served me well, but there are caveats.

Canon's recommended IRE levels will be on the dark side for sure and I've shot quite a bit of footage that was intentionally over exposed compared to that standard. You just have to be aware of how the Canon Log-profile curve (how it distributes its light values) looks. It has a very smooth roll off that starts pretty early—I think this strongly contributes to the 'natural' look. But as you get into the roll off the image will flatten out and you will lose some tonality that might be desirable in skin.

I am sure you have seen some footage with plasticky looking people? This is a result of people misusing log profiles by exposing to high (spreading the butter too thin). Technicolor's CineStyle comes to mind from back in the early days.

Some might also look at Arri or Sony log footage and their sometimes VERY flat profiles, and try to mimic this when shooting Canon Log in less demading scenes: the scene has limited dynamic range so you try to "expose to the right" to improve signal to noise. You then get a washed out, loggy looking scene, that you want to grade in post. But… the thing is that most log profiles were developed for 10 bits or up. In 10 bit you have many more light values to play with and you can afford to be flat. The same cannot be said about 8 bit. Canon knows this and tried to maximise the 8 bit potential when they developed Canon Log. You need to shoot Canon Log closer to your target look than you would a high bit depth, low compression profile/codec combination.

It is this last part, shooting closer to the desired result that has me over exposing at times when I don't need to reserve quite as much roll off for highlights. In this scenario we can improve signal-to-noise by going "lighter".

I'd listen to Shane as I feel he as done quite a bit of testing, but I would also be surprised if he always lands his skin tones as high as IRE 55+
Click to expand...
 
For the most part Canon hit the nail on the head.. I do recommend doing your own tests though. Set up a nice soft light source and push record. After my own testing I found that between 32-38 on the IRE are IDEAL. Anything above that and things start looking "off". There will always be variables but keeping skin tones within that spec will keep skin tones inline.

skintones.jpg
 
Last edited:
You must log in or register to reply here.
Back
Top