In ‘Cinematography: Theory & Practice’ Blain Brown writes, “RAW, in this context, is an absolute scale based on the output of the sensor. It is not necessarily related to the viewing image in terms of brightness values. […] This is, of course, the basic concept of shooting RAW vs. shooting video that is more or less “ready to go.” Shooting RAW/Log is not about producing a final image, it’s about producing a “digital negative” that has great potential further down the line. The downside is that the images are not directly viewable and this makes using exposure tools like zebras and histograms pretty much useless —they can only be used as approximation.”
And for us, the single biggest downside of shooting ETTR is not being able to view the image on the LCD because it’s too bright. It is no longer WYSIWYG.
Brown then goes on to outline several different exposure strategies and concludes that, “In practice, cinematographers rarely use ETTR on feature films or other long-form projects.” From the reading we’ve done, the issue DPs have is not that ETTR doesn’t exploit the sensor’s capabilities so much as that, when grading hours-long projects, it requires more work in post to realize those benefits. Then there are cinematographers like Erik Messerschmidt, who alternate between approaches according to the circumstances.