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Base ISO for Sony A7
Posted: Sun Sep 28, 2014 8:50 am
by Jens Peermann
Desperate to know the base ISO for the A7, I so far found everything between 50 and 200 at various forums and blogs. A DXO DR chart I saw peaks somewhere between the 50 and 100 marks (meaning it's 64 or 80), but that chart refers to measured ISO which may not be the same as the ISO selected on camera.
I hope someone can de-puzzle me. Thanks
Posted: Sun Sep 28, 2014 9:00 am
by Mike in O
100 iso
Posted: Sun Sep 28, 2014 9:09 am
by Royce Howland
If you're after the "base ISO" from a pragmatic standpoint, i.e. the ISO at which signal-to-noise ratio, dynamic range, etc. are maximized -- then the DXO data gives the answer. It's ISO 50, which is the camera setting that's measured somewhere around 80 in the DXO charts. You can see camera ISO vs. measured ISO on the first chart, "ISO Sensitivity".
Actual base ISO may be something different, I suppose.
Re: Base ISO for Sony A7
Posted: Sun Sep 28, 2014 9:47 am
by signgrap
OK I have the same question for the Sony a7R:
What is the base ISO with base meaning the best signal-to-noise ratio, dynamic range etc.?
Re:
Posted: Sun Sep 28, 2014 4:22 pm
by Jens Peermann
Royce Howland wrote:If you're after the "base ISO" from a pragmatic standpoint, i.e. the ISO at which signal-to-noise ratio, dynamic range, etc. are maximized -- then the DXO data gives the answer. It's ISO 50, which is the camera setting that's measured somewhere around 80 in the DXO charts. You can see camera ISO vs. measured ISO on the first chart, "ISO Sensitivity".
Actual base ISO may be something different, I suppose.
Thanks Royce. Looks like ISO 50 is the same as 100, only that it gets overexposed by one stop and that's where the extra range comes from.
Dick, It's pretty much identical for all three of the A7 family:
Correction: I planted the wrong chart. Here is the Dynamic Range comparison:
Posted: Sun Sep 28, 2014 7:04 pm
by signgrap
If I read the above chart correctly it looks like ISO 80 may have the most DR.
Is that an accurate interpretation for the a7R?
Re:
Posted: Sun Sep 28, 2014 7:22 pm
by Jens Peermann
signgrap wrote:If I read the above chart correctly it looks like ISO 80 may have the most DR.
Is that an accurate interpretation for the a7R?
If I read Royce's answer correctly, DXO measured 80 when it was set to 50. So for maximum dynamic range and best signal/noise the camera should be set to 50.
That's at least what I am going to do from here on, until I find another setting to be better.
