In article , Me
wrote:

The Olympus E-M1 II has the lowest noise at ISO 64 (at the cost of a bit
less dynamic range) but the highest dynamic range at ISO 200. So what
would be the native or base ISO of the sensor?
How would that be defined?

Unless the camera maker doesn't specify this specifically, there is no way
to know when the sensor output is boosted or not.

there is.

Yes.
and also the comment that:
"The Olympus E-M1 II has the lowest noise at ISO 64 (at the cost of a
bit less dynamic range)
makes no sense.

it does if you think about what they're probably doing, which is simply
overexposing (their claimed lower iso), thereby blowing the highlights,
resulting in less dynamic range.

based on the above description, the native iso is around iso 200, but
actual tests would need to be done to find out what it really is

Anyway, as Scotty said - "Ye cannae change laws of physics"

http://photonstophotos.net/Charts/PD...OM-D%20E-M1%20
Mark%20II
But wait - Olympus appears to have done so.
So either they're bull****ting about actual ISO setting (which they've
done before) or bull****ting by applying noise reduction to raw files
(which they've also done before), or bull****ting about both (likely).
So if you /think/ when it's set at ISO 6400 - it actually is, and you
/think/ there's no NR applied to raw files, and are happy with the
result, then enjoy.

of course they're bull****ting.

olympus is well known for that, although nowhere near as much as sigma.