Since normal Rec709 can only contain a certain amount of Dynamic Range, camera makers came up with an innovative way to bring out as much detail as possible, by squeezing the higher dynamic into the space of standard 709 screens.
The result doesn't look entirely pleasing, it usually results in a greyish, flat, deadpan image that is in no way nice to look at unless you wanted a super washed out feel. However when graded it becomes some of the nicest looking imagery imaginable.
When you unleash the footage hidden behind the greys you notice just how much the sensor has retained, with dark shadows but also white highlights in the same shot well exposed.
However this footage is a lot harder to grade that traditional footage, and even requires different settings when shooting. I found out in a vimeo tutorial that the best way to shoot the footage is between 1-2 stops overexposed, as Log tends to underexpose the footage significantly, and while it can be pulled up in post it for some reason makes the footage look incredibly ugly to look at, with noise everywhere.
With my new A7S, it has the ability to record Sony Log (S-log 2) onto the SD card, as of such I was quite excited by this, though soon learned that there is indeed a lot more to Log than you expect even if you are prepared
Even when Luma and Colour corrected the image still looks annoying, aesthetically pleasing, but still very annoying. The footage has a cinematic quality that is unrivalled by anything except perhaps RAW.
I have since posted onto movie pages on Facebook to see if I could get some answers on the best way to expose for S-log. The main response that I got back was to make sure that when I overexpose I watch the face of the subject and make sure that I do not blow out the mid tones (skin) otherwise as you can see despite it not clipping my face is a little too bright even when (as seen on the left of the screenshot) the levels have been brought down far below he top of the highlight range.
Another problem might be to do with colour temperature, this camera does not do good with badly set colours and as you can see my face does not look very well done, I look like a mix between an Avatar and a ghost.
I am looking forward to working with S-log and all the other picture profiles that this little camera comes with, I've always wanted to get more cinematic visuals out of my footage and this I found was probably the best way to do it.