DxOMark published the test score of the Pentax 645z medium format camera and it is on the top of the list (with a score of 101):
Here is a quote from DxOMark:
The new RX1R II achieved an excellent DxOMark score of 97 points, with individual scores of 25.8 bits for color sensitivity, a wide 13.9 EVs dynamic range at base ISO (albeit slightly lower at base than the best tested), and a very good low-light ISO score of 3204 ISO. In terms of rankings, only the Pentax 645Z with its physically larger 43.8 x 32.8mm CMOS sensor (nearly 1.7x the surface area of a full-frame 35mm sensor) is ahead by just over a half-stop in noise levels.
