Quality & Size Options

The A550 supports two aspect ratios, standard 3:2 and widescreen 16:9, in the sizes shown below.

Two JPEG compression choices are available, Fine and Standard. RAW files can also be shot, either on their own or combined with a large JPEG with Fine compression.

Dynamic Range (9.39)

The A550 is specially built to produce high-dynamic-range photos, using a special shooting mode that combines two images taken at different exposure settings in-camera to create an image that maximizes detail in the highlight and shadow areas (see details in our Exposure section). Even without using this neat trick, though, the camera delivered strong dynamic range performance. In fact, the A550 outscored all the other cameras in our test group by a significant margin.

We test a camera’s dynamic range by shooting a Kodak stepchart, with 20 gradated patches ranging from solid white to solid black, at the full range of available ISO settings. These test shots are analyzed using Imatest to determine the number of visible steps in each photo, then compiled to produce an overall score for the entire test range.

A camera’s dynamic range inevitably declines as the ISO level increases, but the A550 started at a high 7.55 EV rating at ISO 200 and this figure dropped very gradually as we cranked up the light sensitivity. In fact, even at ISO 6400 we still recorded a dynamic range of 4.29 EV, roughly equivalent to what the Panasonic GF1 managed at ISO 800. More on how we test dynamic range.

The closest competitor to the Sony A550 here is the Nikon D5000, but its d-range reading drops to 5.93 EV at ISO 800, where the Sony is still at 6.69 EV. The A550 proves its mettle here against all comers, particularly the small-sensor Olympus and Panasonic, which had trouble with this test.

Image Stabilization (5.50)

Like other Sony SLRs, the A550 provides in-camera image stabilization, so any lens can benefit from the technology. However, in our tests using the kit 18-55mm lens at its full telephoto length, we found the IS system provided minimal improvements. We test image stabilization based on the improvements in image resolution produced with the system turned on versus shots taken with the system off. The camera is mounted in a custom-built, computer-controlled rig, shooting separately in both horizontal and vertical orientation and with low and high levels of shake. More on how we test image stabilization.

Measured at low shake levels, roughly what you’d expect from someone standing still and holding the camera with both hands, we found slight improvements when shooting at shutter speeds below 1/30 second.

Cranking the shake up to a higher level, which you might experience when shooting while moving quickly, the IS system actually produces poorer horizontal shake results at high shutter speeds. There is a consistent, modest blur reduction when shaking the camera vertically, which becomes significant as we move to the slowest shutter speeds.

The A550’s image stabilization performance is about even with the lens-based stabilization used in the Nikon D5000, a bit better than we found with the Panasonic GF1, but none of these cameras came close to the improvement we measured using the Olympus in-camera image stabilization.

Sony includes an interesting on-screen SteadyShot scale in the lower left corner of the LCD when shooting in modes where shutter speed is set automatically. This five-bar indicator shows the camera shake status; the fewer bars shown, the more likely a shot will be free from blur.

Image Stabilization Comparison Table			Expand
	Low Shake IS Off	Low Shake IS On	High Shake IS Off	High Shake IS On
1/500
1/250
1/125
1/60
1/30
1/15
1/8