The FX6 and log exposure for commandos

did said:
Sure, but again these measurements are made at sensor output in photo mode and it's difficult to predict what they become in video mode at the end of the chain.
It's used mainly by the astronomers who are looking for the best compromise between exposure time and sensitivity.
In video I think it's more complex, there are other parameters and for my practical use I would more follow Doug's tests than the RAW measurements in photo :)
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To be certain, evaluating the final output is all that really matters. Nevertheless, tests like these are instructive for determining what's going on under the hood
 
Doug Jensen said:
I think this thread is more about noise levels than DR, but since the two are very related this chart is useful. Mr. Claff seems to have done some serious testing, and I respect that. Unless someone shows otherwise I will accept his analysis that there is an almost imperceptible change around 400-500 ISO. I have not done any tests of my own in the range, but the difference is so slight it would be hard to notice a less than 1EV difference in regular shooting if you weren't looking for it. As we can see from the chart, there is no changes in the 3200 - 4000 range. My testing showed the same thing --- which is contrary to what JimGao's Youtube heroes claim in their half-assed review videos.
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Base iso is different for Slog3 and S-Cinetone on FX and Alpha cameras.

Base iso rating of a profile is affected by the gamma curve


Doug Jensen said:
Three things are clear:
The A1 is not a dual-ISO camera, despite JimGao's claims.
There is no advantage to cranking up the ISO beyond what is minimally needed to get the necessary exposure at anywhere along the ISO scale, despite JimGao's claims.
People shouldn't make claims about stuff they have no clue about.
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Just because it isn’t big doesn’t mean it isn’t there.

Have you seem the hi base on the Venice 6K? yeah, it isn’t some miracle. The only reason the A7S3 hi base is such a big deal is because it is a crazy 4stops above the native base iso. When you consider that the A1 competes or even beats the A7S3 in iso performance at iso6400, it has to make you wonder how a 50mp camera is competing with the purpose made 12mp low light demon? At least consider it a base boost. As even i’m not going to call it true dual native iso. But just consider that the A1 and A74 are using a hi base in an invisible way to prevent image degradation at higher iso’s. Because you’ll notice that traditionally cameras fall apart in image quality shortly after a two stop push. They don’t suddenly improve in DR, or suddenly 3stops push is indistinguishable from 2stops. Usually 3stops is when we decide to find more light or a faster lens, not “there’s no difference!”

Where a lot of this is moot point territory, is that the A1 doesn’t seem to give an option to choose which base iso to use, so it still makes sense that i should have chosen to say FX9 instead of A1 as a reference. But now that we’ve been on the week long journey of a tangent, i went from uncertain about the A1 to now being fairly certain the A1 has a second base iso. initially, for the sake of staying closer to topic, i was ok with dropping the idea that the A1 was dual iso, but now i’m fairly certain it has a bass boost of some sort.

I genuinely hope this discussion helps you in your work, and talking to your students.
 
Reading all this noise trying to get some useful information about my mysterious FX30, and where Hi and Low bases are when using S Cinetone ... any other tips are desperately welcome.
I shot a very low light museum installation (S LOG3 and very cranked ISO) hours after I took the camera out of the box and got disastrously high noise. Next time I'll read the directions! :-))
 
Depends on the level? If you had it at 100, your monitor could be completely washed out with no zebras where you can't even see the picture (or barely), but you still wouldn't have clipped and can drag everything down in post.
 
scorsesefan said:
Do you guys completely back off your zebras when exposing slog3 whites/skin or do you leave a little?
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I leave a little and when anyone says they are exposing for, for example, 'whites at 77', I assume they mean that at 77 there is a touch of zebra on the brightest (important) whites.

Does anyone here worry about having skin tones too high? Slog3 has no shoulder so in theory, as long as you don't clip, it's no problem to put skin in the final couple of stops to then bring it down in post. Or am I wrong about that?
 
NorBro said:
Depends on the level? If you had it at 100, your monitor could be completely washed out with no zebras where you can't even see the picture (or barely), but you still wouldn't have clipped and can drag everything down in post.
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Well, for the s709 MLUT on the FX6 I usually set skin around 60 and whites around 78....
 
scorsesefan said:
Do you guys completely back off your zebras when exposing slog3 whites/skin or do you leave a little?
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Only a fool would set exposure based on someone's skin.
And even if someone did decide to use zebras to set exposure for a face, it would totally depend on the zebra level setting and (for Sony cameras) whether Zebra1 or Zebra2 is being used.
 
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