Here’s a handy chart of the base ISO levels for Sony’s cinema line cameras including Venice, the FX9, FX6, FX3 and FX30 as well as the A7SIII and A7IV. The new Sony FR7 is the same as the FX6. I’ve include the base ISO’s for both S-Log3 and S-Cinetone. If you use other gammas the base levels may be different to the S-Cinetone base level, so these values should only be used for S-Cinetone and S-Log3. You can click on the image for a bigger version or left click on it to download it.
As explained above there is a difference in the way the dual ISO functions work between the FX6/FX3/A7SIII and the other cameras. Venice, the FX9 and FX30 have sensors with two distinctly different sensitivities. These cameras offer near identical performance at either the low or high base ISO. Sony call these cameras “Dual Base ISO” as in most cases the two base ISO’s can be used in exactly the same way depending on which best suits the light level you are working at and a near identical image produced.
The other cameras (FX6, FX3, A7SIII) probably have a dual gain sensor plus additional processing to deliver their 2 distinctly different sensitivity ranges. The result is that there is a more visible increase in noise at the high range (compared to the Dual Base ISO cameras) plus a very slight reduction in dynamic range. However, the noise level in the high base setting is significantly lower than you would have by adding gain to get to the same level and the upper base sensitivities are very usable and allow for shooting at very low light levels.
For more information on Dual Base ISO sensors take a look here: https://www.xdcam-user.com/2019/11/what-is-dual-base-iso-and-why-is-it-important/
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Thank you!!!
Would the levels from A7SIII work for Alpha One?
I believe the A1 is 100 / 500 for standard gamma and 800 / 3200 for S-Log3.
Thanks for this Alister. Isn’t the higher ISO for the FX30 2500 for s-log3?
You are quite correct, I have amended the slide. Thanks for noticing.
Thank you Alister
It’s very helpful to know the difference between Dual Base ISO and Dual sensitivity.
It’s a vague distinction but you have made a practical distinction for those of us who don’t need to completely understand it!
Hi Alister, for the FX30, how did you get the numbers for S-Cinetone? Was that using your own testing by just cranking up the ISO dial until you saw a noise clean-up? It seems that it doesn’t work that way for S-log right now (neither Flexible ISO nor CineEI – it seems that there is no clean-up for Flexible ISO at all when reaching 2500 and the clean-up only happens with CineEI when manually selecting the higher Base ISO). So I’m wondering how you got your S-Cinetone numbers, did you observe a clean-up at 400 ISO or did you get this from some kind of documentation?
I’m using S-Cinetone on the FX6 in custom mode and have an assignable button which switches between 800 and 12800 when I’m.in slog3 in custom mode – is there a way for the camera to use the correct values (320 and 5000) while switching between base ISO? Currently it still switches between 800 and 12800 although I’m in S-Cinetone . thanks in advance
Switch the camera to work in db gain mode not ISO. That way, when you select 0db gain, the camera will be at the base noise level no matter what picture profile you’ve selected.
I would agree, but when using Cine EI or a Mirrorless body that isn’t an option.
Regarding the table, what means “(V3 on)” next to the FX3?
Maybe it refers to firmware version 3?
So I have heard you talk about every 6db of gain adds an additional stop of sensitivity but also double the noise and decrease dynamic range by 1 stops (so SCinetone that would be 9.5 stop appx).
increasing the gain by +12dB (2×2) increase the noise by 4 stops but does that also decrease the dynamic range by 4 stops and of course the same for +18dB (2x2x2) or 8 times more noise but that just seems crazy that it would decrease the dynamic range also by 8 stops. What am I missing here?
Stops of exposure is a logarithmic scale, 1 extra stop, just like 6dB is x2.
So x2 (6dB) is 1 stop, x4(12dB) is 2 stops, x8(24dB) is 3 stops etc.
If you measure noise using stops and you add 12dB of gain you will have the equivalent of 4 times more noise but this is only 2 stops more noise.
Any idea of the A7sIII values apply for the ZV-E1 also?
What about sony A7R V