Sony makes a point of not calling this a "professional" camera, instead referring to it as the "flagship" model of its dSLR line. However, it's priced like a pro model, and its full-frame competitors--the Nikon D700 and the Canon EOS 5D Mark II--are widely, though not exclusively, used by professionals. Finally, with such a high-resolution sensor you need a really sharp, preferably fast lens such as the Zeiss 24-70mm f2.8 we tested it with; lenses such as that are expensive and generally out of reach for all but professionals.
Furthermore, Sony provides some of the most innovative and pro-friendly accessories we've seen, such as its sideways rotating HVL-F58AM flash and VG-C90AM battery grip, which almost exactly mimics the control layout of horizontal operation when shooting vertically. As with other Sony models, the A900 remains compatible with Konica Minolta lenses.
The camera's design is reminiscent of, but not identical to, the DSLR-A700. At just more than 2 pounds, 1 ounce it's hefty, though it's lighter than the Nikon D700 and about the same as the 5D Mark II. A small status display on the top provides some limited information--shutter, aperture, battery, and shots remaining--while the rest of the information appears on the back LCD. Like the A700, the A900 lets you access and edit all your settings directly via that display, which I happen to like. The controls take a bit of getting used to, since many of them look and feel the same, making it hard to remember their locations. It does provide three custom setting slots on the mode dial, which is very useful, and the large, bright viewfinder is a pleasure to use.
The A900 has two seriously crazy-making design flaws, however. First, there's no way to lock the navigation joystick, which you use to shuffle around AF-point selection. If you always use the Spot or Wide AF, which don't move, it shouldn't bother you. But if you use the Local AF like I do, the selected AF point frequently gets changed by accident. Second, the Preview button is also far too easy to trigger accidentally, and when set for the Intelligent Preview it switches the camera into a different mode you have to escape. Everyone I handed the camera to accidentally triggered it. Click through the slide show for more analysis of the A900's design. And while it's not really a design flaw, the A900's mirror is unusually loud.
Unlike its competitors, which use lens-based image-stabilization systems, Sony opts for in-body sensor-shift image stabilization, now dubbed "SteadyShot Inside." One of the A900's distinctive features is the aforementioned Intelligent Preview; hitting the depth-of-field preview button shows a temporary capture of the scene on the LCD, where you can tweak parameters such as exposure, white balance, shutter speed, aperture, and so on, and get a near-live preview of the changes. It's quite a neat idea, but in practice, I found the LCD didn't represent the image accurately enough to make all but the most basic judgments. It also supplies the typical array of features you'd expect to find, including Creative Styles, for customizing contrast, saturation, sharpness, brightness, and Zone (which preserves highlight or shadow detail, depending upon the setting); D-Range Optimizer (DRO) for expanding the dynamic range; and exposure (+/- 3 stops at 1/3 or 2/3 stop increments) white balance, and DRO bracketing. Some pro-oriented features include a compressed Raw format that records 8-bit data instead of the standard 12-bit; (you can read an interesting discussion in Dyxum.com's forum that was raised for the A700 if you're curious); the capability to fine-tune the AF to compensate for back- or front-focus problems (unlike Nikon and Canon's midrange models, the A900 only supports a single setting); and the capability to customize the operation of the buttons and dials. (You can download the PDF version of the manual for more details of its features and operation.)
To support the huge bandwidth required by its large images, Sony supplies the A900 with not one but two of its Bionz image processors. That helps the A900 maintain its respectable close-to-5fps burst rate (though even with a fast UDMA memory card, such as the 4GB SanDisk Extreme Ducati, the buffer fills quickly) and keeps high ISO shots from taking too long to process and save.