I’ll be reporting in great detail on the 645D, but here are my initial impressions.
Pentax “gets it”. This is a camera that a photographer can use, not a frankencamera made with 1990's concepts. Pentax obviously put thought into the design. It’s feature list ticks off 90% of my beefs with other medium format cameras, lacking (sadly) Live View like all the others, but that’s a sensor technology issue.
The Pentax 645D is relatively bulky because of its large mirror box, but not very heavy for its bulk. With the 55mm f/2.8 lens, very comfortable to hold and shoot. It is festooned with useful buttons, perhaps more than really needed, and I quickly concluded that it’s the best designed medium format DSLR yet offered in terms of usability. I hardly needed to check the manual, it’s a very well thought out design, clearly the thought leader in features and functionality over other medium format cameras. And the rear LCD blows away the sub-consumer-grade screens in other medium format cameras and backs, even those costing 4X as much. The controls for zooming, etc are far more usable than the Leica S2 or any other medium format camera I’ve used.
There are some disappointments however. The HDR feature works only with JPEG files (is that a joke?). Speed of shooting raw is slooooooow, even for landscape work. We’re talking roughly 4.5 seconds to save a single RAW file, and you can’t see the image or its histogram until saved. You can shoot 1.1 frames per second, but you just have to be patient to see what you’ve shot.
The slow save speed must be due in part to the dubious choice of SDHC for storage; the SanDisk 32GB cards I have are about 1/4 the speed of the SanDisk CompactFlash cards that I favor. IMO, the SDHC format is too damned small and easy to lose or misplace, as well as being vastly slower than Compact Flash (The Leica S2 can write a 37.5MP image in 1.25 seconds with a SanDisk Extreme Pro CF card).
In spite of my concerns about the 55mm f/2.8 lens, results so far show it to be a very high performer, and very respectable even wide open at f/2.8.