Quote Originally Posted by John King View Post
Are you sure you are looking at the MkII ?

The MkI DR is lower in extended low at Bill's site, but the PDR for the MkII remains much the same. This appears to have changed since I last looked at it about 12 months ago. Or I am going dippier than I thought I was? Always a strong possibility!

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

Got to post this. My tablet had to be rebooted because it spat the dummy!
Hi John, yes. Looking at the same chart from Bill's site.
And as would be expected, the extended low range is more or less exactly the same as the base iso which for the EM1.2 would be ISO 200. It basically flatlines below ISO 200.
Meaning, there would be no gains from using the low setting compared to ISO 200, but only to produce an image that has a lower brightness than an ISO 200 shot, if the same exposure was used.
There would be no loss either, they are the same except for how the camera subsequently treats the data to produce the final image brightness. The way the EM1.2 does it, I'm not sure if it is purely digital scaling or otherwise but I think that's what you were referring to when you say that EM1.2 shifts the tone curve for the jpeg with a slightly different shape?

By no gains, I mean that the sensor is not able to accept a higher exposure before saturation at the extended lower ISO setting so there would be no gains in DR compared to a 'true' lower setting eg. ISO 64 on D810 and D850 where you'd expect DR gains at the lower 'true' ISO settings.
I know I said no highlight headroom before, but I actually meant no increase in DR but I wrote highlight headroom because I was referring to a situation where I ran out of shutter speed if I wanted to use f1.4 in bright conditions.

I know what you're saying in terms of digital gain on the old 4/3 cameras however digital scaling doesn't have as much penalties as it once did due to the very low read noise in today's sensors. We're starting to approach ISO-less or ISO-invariant sensors where there would be no difference and possibly even improvements by leaving ISO at base all the time and completely scale digitally.