LUT False Color issue

[Xiaosu]

We are shooting on two MiniLFs and are seeing the following issue:

We have false colors with Monitoring-based false color enabled, but are not seeing anything yellow and red although it‘s very clearly over.

It says this in the manual:

When a HDR ALF-2 look file is loaded and activated in the camera, false color mode automaticallyswitches to 'Log C-based'. This is because HDR look files do not generate video signals over 75%,which means that overexposure might not be indicated correctly in 'Monitoring-based false color'mode.When you are using a look file that does not utilize the full signal level range and you activate falsecolor on a monitoring path where Look processing is active, false color will not indicate over- orunderexposure. This specifically applies to Rec 2100 PQ Look files, as they level out at a maximumsignal level of 75%.When using look files with extreme color grading, it is possible for 'Monitoring-based' false color toshow an inaccurate result

But we are not using a HDR LUT.

Are we overlooking something?

Thanks

[Anders Holck]

If you are using a custom LUT/lookfile, make sure that the LUT when created in the grade can actually reach full video out. (also make sure you are at 800 iso or above, below 800 might not reach 100% video) If the colorist has lowered the highlights in the grade to a lower level, false color will not reach the upper colors in monitoring based setting. Just check with a waveform on an external monitor where clipping lands with the custom LUT active, compared to the standard rec709 LUT.

I prefer to always set the Falsecolor to logC based as it then relates to sensor clipping, and is not modified by the output levels of the lut or the iso.

[Jan Heugel]

Dear Xiaosu,

feel free to mail your look file to digitalworkflow@arri.de and we will have a look at your look

Cheers,
Jan