The IQ250 is an incredible medium format digital back, put on a medium format body that functions well enough, with a selection of available lenses that are top of the line. I wanted to try one out last summer, so I put together a quick bridal shoot to test it out. The hardware is honestly beautiful, you feel like a better photographer when you hold the medium format body in your hands and look through the enormous viewfinder.
The dynamic range was interesting, even though it uses the same sensor as the Pentax 645z it had a much different file. The Pentax has multiple stops (~5) of usable data in the shadows before you saw color noise or banding. The IQ250 would get color noise almost instantly when you raise shadows, worse than my Canon at base ISO. On the other hand, it was almost impossible to blow highlights with the Phase one.
That being said, I don’t think I could see myself using this camera on a wedding day. The live view is unusable, the autofocus has no visible point in the viewfinder or confirmation that you’ve focused, the buffer is slow, and the files are TOO big(well over 50MB). And the fact that its sensor is a heavily cropped version of 645 also bugs me.
If I had a commercial shoot in studio like conditions, with somebody else being trusted to edit the files, I’d shoot it in a heartbeat.