Highlight stops and sensor banding

BDowie

Hi all. New Edge 6K owner. Great to finally have this camera. Have been doing a few test shoots to better understand how it works, and mostly going well, however there are a few things I’m unsure of, and slightly concerned about.

The first thing, is that when scrolling through the different highlight stop options, in ISO mode, sometimes there is a colour shift. Shadows are lifted, and shifted towards magenta. The below frames are ISO 800, with 6.0 highlight stops (the magenta image with lifted shadows), and 6.3 highlight stops (in my opinion the more normal looking image). Anyone care to explain what is going on here? Surely this isn’t normal behaviour?

Secondly, I’ve noticed that when underexposed, there is very visible horizontal green banding through the image (see dropbox link for original file). Again, I don’t know what is going on here, but this can’t be normal? I’m wondering if my sensor is okay and functioning correctly as it should be? Of course I don’t plan on underexposing like this, and when exposed correctly, it seems fine and produces a great image, but it doesn’t feel great to me that the sensor does that. I would love an explanation to put me at ease.

https://www.dropbox.com/sh/k0nhtiewijr4k96/AAC13wSfoZ-LMD3YgzdYZx5ba?dl=0

My Edge is an ex-demo one, and has the latest firmware 7.1(4)

Thank you Jerome (or anyone else) for your help.

Ben

Jerome

BDowie hey before starting with a big explanation, we want to suggest you to do a black balance. Simply power off the camera,
hit the menu body and hold on to it while you power the camera, you can release the menu button after 4 long seconds.
Now you are in calibration mode ( yellow letters will say calibration mode so you know if you powered in calibration mode succesfully).
Now search for calibration mode (one of the last menu options), and do a black shading, . close the iris, put a lens cap, and try to avoid to sunny conditions ( to ensure no light is coming in). and do a black calibration, this should get you rid of most of fpn artefacts, like scanning cmos lines and such, Please understand that Kinefinity doesn’t do denoising, so these artefacts should clean easily with a slight noise reduction in post, but a proper black balance now and then should clean most of it. The higher the highlightstop setting the more hyou dig in the noise. Try to start with a setting 4.3-6.0 dont go higher is our suggestion. Please let us know if you managed to do a black shading

BDowie

Jerome thanks a lot for the response Jerome. I should have mentioned, that I did actually do a black balance before posting, to see if that would fix the issue, but it didn’t seem to make much of a difference. I’m not concerned with noise (I think this camera produces very clean images compared to my Red Komodo), but I was more so just a little concerned with the obvious sensor banding when under exposed. I just haven’t seen that on a camera before, so wasn’t sure if my sensor was performing correctly. As I said though, when exposed correctly, there doesn’t seem to be a problem. So perhaps I don’t need to worry about it? Regarding using a lower highlight stop (4.3-6.0), do you find that this still results in a nice highlight roll off, and enough range in the highlights? Thanks again.

Jerome

BDowie a bit of sensor banding is normal on any camera, most camera use heavy temporal and spatial noise reduction in camera, (but at a low profile due to low quality gpu), we have a tutorial how to get rid of this lines completely, but as you noticed these lines are deeply hidden, however try not to increase the highlightstop too much, we rarely go beyond 5. For a tutorial of removing scanning lines you can go HERE.

Roll off is a myth.. a sensor has a so called well capacity, and simply clips or doesnt clip. Sme cameras add a hue sat dim map on top of a ccm,
but doing this in post will yield the same effect except that when its done in-camera its hard to reverse, lets say impossible. Basically with any digital camera you want to expose to the right but wihout clipping too much, so exposing is alwa a matter of compromising between shadow qulity and highlight quality, in shadows there is no hard clip due to rolling into random noise. For every given scene you have to find the good balance, you could use zebras in daylight, set the iso to the very lowest vaue (the least amount of noise), then start to expose until certain precious regions of the image are clipped, then roll back until its unclipped, chek your shadows in log, see if it still holds up enough for grading. In such case the image might look too dark or too bright. In such case we use luts to print down or print up the image, because in cine ei, you can not change analogue iso, like on many cameras. Of course on a alexa 35 you dont have to worry about clipped highlights or clipped shadows, so the future will be fun, but for now, its always a bit of a chess game to get the best amount of data. we dont go over hs 5.0 annd use ettl and ettr luts to display the image correctly on our monitor. hope this helps

BDowie

Jerome thanks Jerome, appreciate the info, very helpful to know.