Exposure exposure exposure

[illia]

Hi, this might be a little overexplained but I am a little bit confused about exposure in digital media where Log curves o raw formats are used. In fact I would say that my question would also be applied to analog cinematography in the way the latitud is increased regarding the output media.
Let's say our device can handle 12 stops of latitude, and our final output media is going to have 7 stops. In digital, as the slog curves offer a low contrast image we are used to work wuth luts that approach the image to the final look we want... My question would be if it would be intelligent to expose the image according to the LUT (the white levels and medium tones) and then check the log or raw image to see if we stay in the range the camera can handle, or if it's better to expose using the raw view, or the log uncompressed image.
I know it can seem evident to use whatever the biggest image quality we have to have an accurate exposure, but, if we have a grey point at 35 IRE and a white point at 70 IRE using slog, and after the must be conversion those levels are going to be adjusted to 45 and 100 IRE, it seems reasonable to start with this data for the overall exposure and then checking the sensitive areas (highlights and shadows) in our true signal raw or whatever... What do you think about it?

 

[Matt W.]

That's a tricky question...probably a needlessly tricky one. One of those situations where the more you think about it the harder it is to answer.

I guess the central issue is whether you expose for the recording medium (negative/raw/ungraded video) or the viewing medium (print/graded video)? There's no right answer. Cinematographers who like to finesse the image in post will do the former; those who want to lock in the look in camera will do the latter. Personally, I aspire to the latter but err on the side of enough latitude to fix continuity issues, etc. I'll usually leave the blacks a bit too flat so I can pull out some detail if I need to. The fact that baked-in white balance and set ISO values offend proponents of raw video is ridiculous, though. You should at least be able to decide that on set! Likewise, just because you have so many stops of dynamic range doesn't mean you need to fill them. Choose your ratios, most importantly on faces, based on the look you want to end up with.

No matter how you shoot and grade, the final product is what matters. If you end up with it primarily through grading or through in-camera manipulation it doesn't matter so long as it looks good in the end. So normally you're lighting for something in-between the negative and the print. This is complicated, of course, when you have a scene with 10 stops of contrast and your video camera has just about the much dr but the faces are way in the shadows or something and so you have to underexpose with the intention of bringing things up in post to preserve highlight detail. Gets kind of ugly then, and that's when film's compressed highlights make it really nice. You can just expose correctly or slightly underexpose and know the roll-off to white will be natural.