Medium-format digital backs, from Phase One and Hasselblad, have (up to now) used CCDs for their sensors, to obtain great tonal range, 16-bit beautiful color, and a usable ISO from 35 to 100….. any higher, and the noise was unbearable!
Everything changed with the new Sony 50MP CMOS chip, now in the Phase One IQ250 (and soon in the Hasselblad, as well). CMOS technology places processors right behind each sensor, thus enabling noise reduction before the signal is even recorded, hence, great capabilities at higher ISOs!
I had the chance to try out the new Phase One IQ250, which can be set as high as ISO 6400 - I found ISO 1600 to be completely usable. Same astounding tonal range - over 14 stops of exposure latitude - same great 16-bit color, same shallow depth-of-field and smooth tonal transitions from the larger lenses projecting a larger image over a larger sensor…. but now, at much higher ISOs! This is the solution we've been waiting for: when shooting ambient light in low light, or under continuous-light setups (staged for recording motion), and for balancing strobes and ambient at reasonable shutter speeds indoors!
Here're a couple of full-size images, one on the Phase One, the other on a Canon 5D Mk2, (made a couple of weeks apart, as I didn't have the Canon with me when testing the IQ250)
And here're closeups, with the Canon at 100% (hence, a 12"X18" print), and the Phase One as a crop of the same view, as if also printed 12"X18"
Noise? Details? Color? Draw your own conclusions…….