The Phase One IQ250 ($34,990) is the first medium format image capture device with a CMOS image sensor to come to market in recent memory. Two other CMOS medium format cameras are set to ship this year; the Hasselblad H5D-50c was announced at the same time as the 50-megapixel IQ250, and the Pentax 645D 2014 has been previewed at the CP+ and WPPI photo shows. But the Phase One features the most versatile design of the trio; it's removable so it can be attached to a variety of different camera systems. With the right lens attached it's able to capture an incredible amount of detail, and its CMOS design adds Live View and gives it a leg up in high ISO capability when compared with CCD systems. It's not the cheapest way to get into medium format—the first iteration of the Pentax 645D is a good place to look if you want to save some money, but it doesn't offer the versatility that the modular design of a removable back provides.

Medium format veterans are well aware of its advantages over smaller 35mm full-frame and APS-C image sensors. The larger sensor allows for smoother transition between colors and light levels, and since longer focal lengths are used to cover a wider field of view, a shallower depth of field is made possible. There's also the resolution factor; squeezing 50 megapixels into a 35mm sensor isn't out of the question, but here the pixels can be made larger while still capturing high-resolution images. The IQ250's pixels are just a bit larger than those in the 36-megapixel Nikon D800. As a general rule of thumb, larger pixels deliver cleaner images at comparable sensitivities.

Design and Interface

The IQ250 measures in at about 10 by 11.5 by 8 inches (HWD) and weighs about 1.75 pounds. It's heavy for its size, but its solid aircraft-grade aluminum construction accounts for this. It's largely a touch-screen device, but there are four physical control buttons, two on each side of the rear display. The color scheme is flat black, and the company offers the back with mounts for its own Phase One/Mamiya 645 system, as well as for Hasselblad H, Hasselblad V, and Contax 645 cameras. Adapters are available for more esoteric Alpa, Arca Swiss, Cambo, Linhof, Toyo, Sinar, Plaubel, and Horseman systems—if you're looking to match the back to one of these, it's not a bad idea to consult a salesperson to make sure that you've got everything you need to make it work.

The display is a 3.2-inch touch screen with a 1.15-megapixel resolution. I had no complaints using it outdoors on average bright midwinter day, but on a similar day with a lot of snow on the ground it was a bit difficult to see it clearly. The touch controls took a little getting used to, but once I had spent a little time familiarizing myself with the menu system I was quite impressed with the way things are laid out.

When you start up the IQ250 you're greeted with four main settings—Play, Menu, ISO, and White Balance. Each can be activated via touch, or via the corresponding physical button. There are some indicators at the bottom of the display—if you're shooting with a CF card installed it shows you the number of photos the card can store, and the battery level indicator is next to that on the bottom left corner. At the bottom right corner is an icon that looks like a comic strip speech bubble; tapping that brings up the options that control how images are shown when played back (one by one or in a grid), and a movie camera icon that brings up Live View (don't expect video recording—Live View is only used for still capture).

Live View is useful for carefully framing a shot, as well as confirming focus. You can zoom all the way into a 100 percent view of any part of the frame, and it's very easy to visually focus at that magnification. I found it to be more reliable than the focus screen that's installed in the Phase One 645DF+ that I was using during my time with the IQ250; but that camera does support different screens, so you can install one that's better suited for manual focus if you prefer. There is a bit of lag if you reposition the camera—movements result in a distinct jelly-like motion, but that shouldn't be a big deal when using Live View to compose shots or check for critical focus before firing the shutter.

Live View comes in handy for precise framing—the 645DF+ (and other cameras to which the back can be attached) has a viewfinder that's designed for full-format 645 sensors; the IQ250 sensor is smaller, resulting in about a 1.3x crop. I was able to acclimate myself to leaving enough room around my subject (and if I shot too wide, there are gobs of resolution, so cropping is not a problem), but there were tight shots for which Live View was a godsend. It's not actually possible to fire a shot with the feed showing on the rear display, but a quick tap of the top left button disables it, and I was able to immediately fire a shot without moving the camera to maintain my frame.

The Camera

The 645DF+ isn't the subject of this review, but I found it to be weakest link in the particular chain that I was working with. I'm used to shooting with APS-C and 35mm full-frame cameras (SLR and mirrorless alike) and while I was expecting the autofocus system to be a bit on the pokey side, I wasn't prepared for just how many shots were just a bit out of focus. Part of this was my pushing the camera to its limits—the shallow depth of field that a medium format system is capable of capturing is enticing, and I was shooting wide open to amplify the effect. Its focus system can only be set for left, right, or center, a far cry from systems that can have dozens of selectable points with which I'm used to working. For my second shooting excursion I took a bit more care, bracketing with multiple apertures and switching to manual focus when I felt that the autofocus system wasn't giving me what I wanted.

Focus system aside, the Phase One body does have the other controls you'd expect from a camera used by pros. There's a mode dial, front and rear control dials, and buttons to enable bracketing, activate the self-timer (interval shooting is also supported), control exposure compensation, the metering pattern, and autoexposure lock. There's a monochrome LCD and current settings are also displayed in the viewfinder. A toggle switch on the front of the body adjusts the focus mode, and there are depth of field preview and focus lock buttons on the front of the camera, next to the lens mount. The drive mode is controlled via a switch that surrounds the shutter release—it can be set to single, continuous, or mirror lockup. When paired with a leaf shutter lens flash sync is available at speeds as short as 1/1,600-second, but only at 1/125-second when utilizing the focal plane shutter. The minimum exposure time for use sans flash is 1/4,000-second, and long exposure fans will be happy to know that the body and IQ250 back can be set for exposures as long as 60 minutes.