Olympus E-M1X and the strange ISO behaviour revisited

[Guillermo Luijk]

Three RAW files from the Olympus E-M1 X, all three with exactly the same exposure (Shutter: 1/6.0 sec, Aperture: f/2.8 ) only varying the ISO setting. RAW histograms:



Tada! again Olympus implementing counterintuitive ISO gains (as with the E-P5 and E-M5 cameras). See here that ISO100 gets higher values in the RAW file than ISO200, crazy!.
The good news is that for the very first time on Olympus, the ISO64 setting seems to be a real ISO with a lower gain than any other ISO. This low gain should provide a tiny peak of extra dynamic range at ISO64.

This strange ISO behaviour may explain the strange DR plot Bill Claff obtained here:

http://www.photonstophotos.net/Charts/PDR.htm#Olympus%20OM-D%20E-M1%20Mark%20II,Olympus%20OM-D%20E-M1X

According to his measures, ISO100 should have less DR than ISO200, and this is fine with the histograms above. However he calculates the same DR at ISO64 as at ISO200, and the histograms show more headroom at ISO64 than at ISO200 for a given exposure.

Regards

[TonyVentourisPhotography]

That is interesting.  I’ve seen that 100 and 64 don’t nearly retain highlight, or display it nearly as good as 200.  In real shots there seems to be a real difference.  And the difference to me has favored 200 and up.  Very interesting what you are showing though.  I’ll have to dig further into the files.  Noise behavior also seems quite a bit different than the e-m1.2 so far as well.