The layout of the A900's body is, not too surprisingly, very similar to the Alpha A700; in fact the rear panels are all but identical, with the same array of controls around the big three-inch 921k LCD monitor. The A900 also shares the A700's highly versatile control interface, and for a professional camera it is surprisingly easy to use. Main shooting functions such as white balance, ISO setting, drive mode and exposure compensation can be accessed via and well-separated dedicated buttons on the top panel (designed to be usable while wearing gloves), or via the joystick-controlled graphic menu, along with Dynamic Range Optimiser options, Creative Styles, metering and AF options and of course image size and quality. Changes from the A700 include the addition of a small and not terribly useful LCD data display on the top panel, while on the main mode dial the A700's selection of programmed scene modes have been replaced with three user-defined custom settings. Personally I find the Sony control system to be far simpler and quicker than the rather fiddly controls of the EOS 5D MkII.
Like all professional cameras the A900 offers a huge amount of creative control. It has shutter speeds from 30 seconds to 1/8000th of a second (as do the EOS 5D MkII and D700), ISO settings from 100 the 6400 in 1/3EV increments, and a versatile selection of Creative Style picture options. There are 13 pre-sets of which six can be selected for quick access. All of the pre-sets can be customised with adjustments for contrast, saturation, sharpness, brightness and "zone", which sets parameters to avoid under or over-exposure when shooting light or dark subjects. As well as this there are separate options for long exposure and high-ISO noise reduction, with the latter having three strength settings, which will be welcomed by the more demanding professionals.
Also in common with other professional DSLRs the A900 has several options for JPEG and Raw mode shooting, including a compressed Raw format, as well as Raw + JPEG and three JPEG mode image size options. This is just as well, because the A900's huge maximum image size (6048 x 4032 pixels) can produce enormous file sizes. Shooting in uncompressed Raw + JPEG mode, as many photographers will prefer to do, can use up around 45MB per shot, so a freshly-formatted 2GB CompactFlash card is only enough for 57 shots. Fortunately the A900 has two card slots, one for Sony's proprietary Memory Stick Duo format, and it is possible to select to which card a particular image will be stored, but you're still going to need a lot of storage capacity if you're planning an extended shooting trip.