Better high ISO performance has been a most desired feature of the M9. The M8 as good as it is at 160/320 starts to run out of gas as it reaches 640 and ,for me ,loses it at 1250. Not just because of the noise,which can be addressed particularly in black and white, but also because of the compression of DR and loss of color saturation.
I found a great opportunity to test the M9 along with the 24/1.4 summilux and the 50/1 Noctilux at the Georgia Aquarium.
I will apologize for the following images as I am sure I destroyed the raw files in creating the jpegs displayed..but you can get the idea.
The first image is the 24/1.4 at 1000 and the 2nd is the Noctilux (shot at 1.4) at 1000. I tried to add about .7 to the metered exposure which still preserved the highlights and gave more room in the shadows.
The 3rd image is at 800 and you can see little difference. The final ..actually a mistake was shot at 160.
My conclusions line up with "the consensus of current reports" ISO 1000 looks like 640 and may actually be better because of the larger file. The shadows had about +1EV of range and the highlights looked good to me.
The files at all ISO appear smoother and have greater color depth...you can beat on them more in the conversions..so in the end the results are better even using a +1EV as the useable ISO range.
Both lens vignetted on the FF..the Noctilux quite a bit. An aquarium is like shooting a light box.
Now if I could actually nail the exposure and could figure out C1 the files would sing.