This paper
http://www.dpreview.com/reviews/sony-alpha-7r-ii/8 seems interesting, quote:
"
Shooting ISO Invariant using S-Log 2
On most cameras it's difficult to take advantage of their ISO Invariant nature because the camera's meter considers you to be hugely under-exposing and, even if your camera will present a preview that isn't related to exposure, the files you shoot are likely to appear almost totally black, making it very difficult to assess exposure.
Sony's S-Log 2 gamma curve: primarily designed for movie shooting, it ends up doubling as a handy way of making it easier to make use of the sensor's capabilities. The ways it does this are two-fold: firstly, because it offers an incredibly flat tone curve, the dark tones in the Raw file that you might want to make use of are pulled up and presented reasonably brightly.
Secondly, though, is the knock-on effect of this tone curve. Because ISO ratings are based on mid tones in JPEGs and the flat tone curve pulls its mid tones from a long way down the Raw file, the S-Log2 mode is considered to be a higher ISO than the normal tone curve. As a result, the lowest available ISO in S-Log2 mode is 800: not because the lower settings are being locked off but because an ISO 800 exposure is enough for a middle-grey object to be represented as a middle grey in the S-Log 2 JPEGs.
Looked at from a Raw perspective and what's happening is the camera is trying to use ISO 800 exposures but with much lower amplification than in standard mode, meaning highlights aren't being amplified out of the file. (If shot with the same exposure values, the ISO 800 Raw files from S-Log2 shooting appear to be somewhere between the ISO 125 and ISO 160 results in standard mode).
As a result, shooting in SLog-2 mode not only provides a more usable preview and output JPEG, it also essentially causes the camera to reduce exposure by 2.5EV to protect highlights."
So, I gave that line of thought a try, set ISO to 800 and took two shots, one with
Picture Profile Off and one with PP7.
First the OOC JPGs, reduced in size only, no further processing.
OOC JPG, PP Off
OOC JPG, PP7
Indeed, when taking the shots, the images appear similarly in the EVF.
Next, images derived from the raw files with Default processing in C1.
Derived from .ARW file, PP Off, Default Adjustments
Derived from .ARW file, PP7, Default Adjustments
Here the PP7 derived image avoids the extremes of the highs and lows of the PP Off version.
And finally the images derived from the raw files with zero adjustments.
Derived from .ARW file, PP Off, 0 Adjustments
Derived from .ARW file, PP7, 0 Adjustments
As anticipated, for PP7 the camera reduced exposure by 2.5EV to protect highlights.
My take: I am going to try this approach with scenes of excessive DR, easily encountered in the "Land of Enchantment". :grin: