Sony Alpha A900

Lens & Sensor

The A900 is not sold in a kit configuration. For test purposes we shot primarily with the TK, which produced the following levels of magnification at the minimum, maximum and middle zoom settings.

Zoom Ratio Examples
24.0 mm	70.0 mm	105.0 mm

The full-frame CMOS image sensor measures 35.9 × 24.0 mm, with 25,720,000 gross pixels and 24,610,0000-pixel effective resolution. That puts it ahead of its primary full-frame competitors in The Great Megapixel Race, with the Canon 5D Mark II at 21.1 megapixels and a paltry 12.1 megapixels for the Nikon D700.

The A900 incorporates an automatic dust reduction system that shakes the sensor itself (already motorized to provide in-camera image stabilization) every time you turn off the camera.

The A900 sensor matches the 36 × 24mm dimensions of a frame of 35mm film, which avoids the apparent magnification that takes place when you mount a lens on a typical digital camera, with its smaller image sensor. With a smaller sensor, only the middle portion of the light coming through the lens is captured — basically the center becomes the entire photo. As seen below, the APS-C camera sensor used in most digital SLRs effectively multiplies the apparent lens size by a factor of 1.6. For the 24-105mm mm lens we used to test the A900, it would shoot like a 38-168mm lens. That means more telephoto zoom out of the same lens, but also crops out the wide-angle areas. With the A900 and other full-frame SLRs, you get the full side-to-side, top-to-bottom coverage the lens is capable of delivering.

Viewfinder (10.25)

The viewfinder offers nearly 100% coverage, a true standout feature, with excellent brightness and easy legibility for the data readout. The diopter control (-3.0 to +1.0 m-1) is located on the right of the viewfinder. There’s a built-in viewfinder shutter, to prevent light leaking in when shooting on a tripod, a huge convenience compared to mounting a cover manually over the eyepiece. The control for this is on the left of the viewfinder. The A900 supports interchangeable focusing screens, including Type M screens that support very fast lenses and Type L screens that are equipped with a grid pattern.

Beneath the viewfinder are sensors that automatically turn off the LCD monitor when you hold the camera up to your eye.

Display(s) (8.86)

The standard for fine viewing in an upscale digital SLR today is a 3-inch LCD with 921,000-dot resolution, which is precisely what Sony delivers here. It’s a handsome display when viewed straight on, though it does begin to gray out noticeably when held away at a moderate angle — not unusable, but not as wide-angle as the Canon 5D Mark II or Nikon D700.

LCD brightness can be adjusted in 11 steps. Sony was clever enough to display a grayscale chart on the brightness adjustment screen, which makes switching settings a lot more meaningful.

The rear screen menu display can be set to one of three modes by pressing the DISP button during shooting. The Detailed Display provides an overview of most camera settings. The enlarged display cuts down on the level of detail, but makes it more readable at a glance.

One handy feature not found in competitive models is the way the A900 automatically senses when the camera is turned vertically (with either side on top) and swaps the screen display orientation to match.

Secondary Display

While the main LCD panel is a thing of beauty and a joy forever, the monochrome LCD on the top right seems like a begrudging afterthought. It’s small (only about an inch measured diagonally), with a minimal amount of information displayed. At least the button to the screen’s right illuminates it effectively.

Connectivity (4.50)

The most noteworthy input/output feature of the A900 is the mini HDMI jack for connecting directly to a high-def TV. It’s located on the left side of the camera back, in a compartment that also provides a proprietary jack for standard-definition video and USB data connection.

On the right side of the camera are two additional jacks, under separate covers. The top one is used to connect a wired remote control, the bottom for the optional AC-VQ900AM AC adapter ($150).

There is also a flash sync terminal on the front right of the camera, and an infrared remote sensor on the front camera grip for the included Remote Commander remote control.