Please check the graph I had linked to.
The ISO 200 of the phase one P40+ is measured to correspond to a real sensitivity of ISO 100, this has nothing to do with the base sensitivity of the sensor.
The only think I did is to translate in words what that graph shows.
Regards,
Bernard
Ahh, I see where you are coming from! sorry about that. The problem is that I think you are inferring something from the DXO results that may not be the case (that it is artificially low for highlight recovery). I've been trying to find a description for how DXO is measuring ISO but haven't found one yet and I suspect their results are as much an issue of their test methods as they are the properties of the camera. For instance look at their measurements for the H3dII39 and 50 and which indicate that all ISO settings measured only 46 or 47.
Let me preface the next section saying that I've been shooting medium format for some time and have always preferred it to 35mm. Maybe its psychological but i think it helps me create better images by the very fact it forces me to slow down a bit. and of course once you know how to get the best quality it is addicting!
All this said, DXO numbers give us some useful insight, but still is no substitute for actual use. I got some hands on time with the 645D a month and half ago (albeit brief). The camera has some good points and hopefully a good future, but I just don't think its "there yet."
Pros:
-Great auto focus, smooth quiet, responsive. Hard to tell if it was necessarily faster then phase or hasselblad, but it was more polished.
-Great LCD screen.
-Light, felt good in the hands.
-ISO 800 looked very usable
Cons:
-Normal ISO range was 200-800 and 200 is treated as base and default ISO. (apparently you can do 100 and 1600 with some trickery, perhaps they are treating them as fake ISO like 50 on some Canon?). If ISO 200 looked like 50 or 100 on other backs this would be a Pro, but it looked like 200, I.E. some noise present in the shadows and not as sharp as it could be.
-Buttons everywhere. Some people may find this a positive, personally I didn't like it, but to each their own.
-Viewfinder puts your face right up against the screen and is also not that bright.
-Most importantly Image quality in the DNG files looked more like a 40mp 35mm DSLR rather than the quality I am used to seeing from Phase and Leaf backs. This may be due to ISO 200 being the base, the fact that the camera uses only 14bit AD conversion, or that software support is still quite limited. Either way it was a let down.