Sony's S-Log... only shoot at native ISO?

[AlexTardif]

A bit confused on this... please chime in!

So we want to shoot in S-Log on, say, any of the 4K entry level cameras (A7Sii, Rii, FS5) to get that flat profile and wide DR.  But I keep running into claims that unless you're shooting at the native ISO (1,600 for A7Sii/Rii bodies, 3,200 for FS5) you aren't getting all that DR.  I just watched Allister Chapman's presentation on FS5 and he clearly states that you ONLY want to shoot in S-Log at the native ISO of 3,200, otherwise you're just wasting space because you are NOT getting that 14 stops of DR with any other ISO.  I think I've read his comments on this as well in his A7s exposure guide too (edit: yep, just re-read it and he states the same there)

So, what's the story here?  I see everyone shooting S-Log in whatever ISO they want, but is it somewhat of a waste?  Since the floor is already so high at 3,200, the only way to control your exposure is to use NDs and to stop down (neither of which is all that desirable, especially stopping down).  But, bigger question for me is with A7Sii in low light... since I can't open any wider than my glass allows, what happened to DR when I start cranking up the ISO, to 6,400, 12,800+ while shooting S-Log?  Is my DR reduced to the point where it makes no sense to shoot S-Log?  If yes, then what are the benefits of shooting S-Log then... color grading from a flat profile?

And probably an even more important question is... since you want to overexpose (2-3 stops) while shooting in S-Log, unless you're shooting at the native ISO (the only place where you actually getting the full 14 stops of DR) you really HAVE TO shoot at native ISO, otherwise, you'd be overexposing and not have that DR to work with in post.

I'm still learning, so excuse the ignorance if these are "duhh" type questions!

[BrorSvensson]

A bit confused on this... please chime in!

So we want to shoot in S-Log on, say, any of the 4K entry level cameras (A7Sii, Rii, FS5) to get that flat profile and wide DR.  But I keep running into claims that unless you're shooting at the native ISO (1,600 for A7Sii/Rii bodies, 3,200 for FS5) you aren't getting all that DR.  I just watched Allister Chapman's presentation on FS5 and he clearly states that you ONLY want to shoot in S-Log at the native ISO of 3,200, otherwise you're just wasting space because you are NOT getting that 14 stops of DR with any other ISO.  I think I've read his comments on this as well in his A7s exposure guide too (edit: yep, just re-read it and he states the same there)

So, what's the story here?  I see everyone shooting S-Log in whatever ISO they want, but is it somewhat of a waste?  Since the floor is already so high at 3,200, the only way to control your exposure is to use NDs and to stop down (neither of which is all that desirable, especially stopping down).  But, bigger question for me is with A7Sii in low light... since I can't open any wider than my glass allows, what happened to DR when I start cranking up the ISO, to 6,400, 12,800+ while shooting S-Log?  Is my DR reduced to the point where it makes no sense to shoot S-Log?  If yes, then what are the benefits of shooting S-Log then... color grading from a flat profile?

And probably an even more important question is... since you want to overexpose (2-3 stops) while shooting in S-Log, unless you're shooting at the native ISO (the only place where you actually getting the full 14 stops of DR) you really HAVE TO shoot at native ISO, otherwise, you'd be overexposing and not have that DR to work with in post.

I'm still learning, so excuse the ignorance if these are "duhh" type questions!

The higher iso will make your dynamic range smaller but it will still be bigger than if you would should with a picture style like "standard" or "natural".