I'm working with an Arri Amira and we want to shoot in LogC of course. So i heard that most of the people just shoot in LogC but they don't exposure in the correct way to use really the whole Dynamic Range.
I don't have access to an ARRI anything... but when I was researching how to calibrate one's effective ISO values for any 'digital' camera, I did run across some articles on ARRI Alexa and what principles were involved in determining exposures that allowed for the full dynamic range of the camera to be recorded/available.
Here's an article:
This method requires that you have the ability to display the a IRE waveform, and the step test target.
It seems that a 18% grey card reading shoud be, from the article according to ARRI, around 38% IRE for LogC recording. The author of the article seems to want to place the 18% grey card at 45-50% IRE...
So, one would have to test to calibrate meter reading with its ISO settings, camera ISO setting, to IRE output based on the 18% grey card. (I declined getting to 'is the 18% grey card really 18%...).