Phase One digital backs have struggled with low light and high ISOs. Well, that's not completely correct. Some of the Phase One backs produce literally flawless long exposures up to one hour - they are noiseless. But some of the other backs are limited to around 30 seconds (maybe 60 seconds on a good day) and they don't like moving too far away from their native ISO settings of ISO 35 or 50. You can do it, but you have to make sure you get as much light as you can into the shadows. In comparison to a modern DSLR, it's not so easy.
Well, all that might have changed with the new Phase One IQ250. Unlike existing Phase One backs which use a CCD sensor, the new IQ250 features a CMOS sensor (like DSLRs), so it is much more responsive in low light. The ISO range is from 100 to 6400 and it also allows exposures up to one hour (which is not likely to be necessary at ISO 6400, of course!).
The new back has a 1.3X lens factor (meaning it's like an APS-C sensor compared to a full-frame sensor on a DSLR), a series of micro lenses covers the sensor to focus the light, there's a wonderful live view feature, built-in wi-fi and geotagging.
For more information, I'm sure Richard at L&P Digital Photographic would be delighted to have a chat. Visit www.lapfoto.com.au