Best Configuration for Evaluating ETTR Captures on Fujifilm Medium Format?
ETTR at ISO 100/50, Histograms and More established that camera metering ("+0" metering) can underexpose a stop or more, making ETTR worthwhile for maximum quality.
It concluded that the tools the camera provides make it difficult to determine optimal ETTR. Also that ISO 50, which would be useful if only for better JPEG brightness, is not especially viable given the requirement for mechanical shutter and a misleading histogram.
This page looks at what can be done at ISO 100 to render a better histogram and better JPEG (RAW+JPG) in order to more easily determine the optimal ETTR exposure.
Fujifilm GFX100S: Configuring for ETTR Captures
Includes screencast video walkthrough.
The same ideas apply to the rest of the GFX100 series.