C100: Knee setting not affecting the picture (at all)

[coutard]

Hello,

I'm quite used to use the kness settings when shootings with ENG camcorders (PMW 320, DSRs...) and it's often quite useful.
even if you don't set any Knee point or slope, toggling the knee always shows a result...I like to set the point at 90 and the slope at -10, and I put the knee saturation a bit up so my "downed" whites are not too grey.

I've been shooting C-log since I have my C100 but last week I was on a short delay production, so I used a profile I found on the web which is quite nice and doesn't need any grading, nice skins tones, and gives a flattering image with nice contrast and saturation.

but at the beginning of the day, I was shooting a woman in the shadow, it was in the morning, and suddenly the sun came up and the background was overexposed, and I had no light with enough power to counterbalance the sun....so I tried to get that down a little while going to my profile settings and tried to pull down the knee setting

so I set my point and slope and try to toggle it on and off....absolutely no change. none. even with a drastic setting..
then I had to shoot fast so I just forgot about it

anybody ever tried / successfully used the knee setting on the C100 ?

 

[Pave1]

Read the manual. Canon turn off the knee function for all cine gammas (and I understand why, it is a duplicated function in this case).

If you will use normal1-4 gamma, knee will start to work (change DR from 107pct/1:500 contrast to 300pct - 1:1500 contrast).
Basic cine1 gamma has also about 300pct DR (knee is turned off), only Canon-log gamma has about 800pct (1:4000 contrast; knee is also turned off).

If the camera's dynamic range can't take some high dynamic range scene with canon-log gamma then no knee can help to you.

 

[coutard]

I did read it, but didn't remember that.
Thanks for the detailed answer, it is interesting !