knee settings

[Dejan Šuc]

Hi guys,
why should I bother with knee values under FS700 profiles? Overexposed areas can be easily corrected with YUV curves (linear correction) in any NLE program.
I am looking for any useful advice.

Thanks in advance.
Dean

[Olof Ekbergh]

There are no hard and fast rules. It is up to you and your style of shooting/editing.

I came up with my PPs the same way I set up every new camera. I spent time playing with it while looking at scopes and eval monitor, under many different lighting (contrast) conditions.

I shoot for a decent look out of the camera w/o sacrificing DR.

These are the settings I use, PP2 and 3 are my standard goto settings, I have 2 copies so I can tweak one in the field if need be and then quickly go back:

[Tim Dashwood]

Originally Posted by Dejan Šuc

Overexposed areas can be easily corrected with YUV curves (linear correction) in any NLE program.

Not if the overexposed areas exceed 108 IRE !

If you are attempting to capture a high contrast scene and retain highlight detail then knee control can be really helpful in squeezing out a few extra stops of latitude.
See the "White clip & Knee" video on this page. http://www.dvinfo.net/video/tutorials/prohd I made these tutorials quite a few years ago for the JVC cameras but the concept hasn't changed.

Of course, if you are using S-Log2 on a v3.0 FS700 the knee setting is irrelevant because the response curve is predetermined and cannot be adjusted. The same goes for toe (black) and most other PP settings when using S-Log2 (or ITU709 800%).

[Noah Yuan-Vogel]

Originally Posted by Tim Dashwood

Of course, if you are using S-Log2 on a v3.0 FS700 the knee setting is irrelevant because the response curve is predetermined and cannot be adjusted. The same goes for toe (black) and most other PP settings when using S-Log2 (or ITU709 800%).

Actually the knee function still operates in SLOG2, as does black gamma, sharpness, color depth, etc. This then begs the question, what are the correct settings for these in SLOG2? I assume SLOG2 was designed to be used with all those settings at default, but it is not clear. It would be nice to be able to turn those functions off and lock in pure SLOG2 or it would be nice to be able to tweak SLOG2 into a flat but useable image that is better for SDHC recording and/or no-grading jobs, but saturation does not operate and black gamma is not strong enough to make SLOG2 into a final image. I always shoot a tweaked Canon log profile when on the C300 so that it looks close to C-LOG but contrast and saturation and saturation is pushed up a bit so it looks good even without any grading, I wish this was possible on the FS700. As it is, there is no real good way to monitor properly while shooting SLOG2 on the FS700, and no way to get it's benefits without absolutely requiring a LUT/grading in post.

[Tim Dashwood]

Sony should have made those setting non-functional when S-Log2 is the selected gamma. You can adjust them all you want but they have absolutely no effect when S-Log2 or REC709 800% are in use. It's the first thing I tested with my scopes when I got the upgrade.

Monitoring properly requires a LOG to REC709 LUT box or monitor that can display a LUT. The Odyssey7Q can also do it.
I've also added the functionality to the next version of my OS X app Stereo3D CAT. I might release a version on the app store just for LOG monitoring.

[Noah Yuan-Vogel]

Actually they all do work according to my quick tests. In SLOG2, black gamma definitely has an effect on the image, as do knee, sharpness and color depth. I remember because I spent a while playing with the settings trying to figure if I could correct the SLOG2 images a bit in camera so I could get the benefits of SLOG2 (it doesnt have the colored highlight problem) while also not requiring grading and giving my AVCHD a better starting point so it doesn't have to get pushed too hard to get a corrected image in post, but the black gamma function is too weak to restore contrast fully, and saturation is stuck too low for a corrected image since you can't change it.

[Tim Dashwood]

Were you testing with scopes or just your eyes? My scopes showed no effect.

[Noah Yuan-Vogel]

My eyes, I could clearly see those functions change the image.