Quality & Size Options

The Sony A900 can shoot at three aspect ratios: the native 3:2 format, widescreen 16:9 and a reduced-resolution APS-C size capture for use when a lens designed for a smaller sensor size is attached.

JPEG images can be saved at three compression settings: Extra Fine, Fine and Standard. In addition, there are two RAW file formats available, a straight RAW file and a compressed RAW (cRAW) which will be about 60-70% the size of an uncompressed RAW file. Either RAW format can also be shot as RAW + JPEG, with a Large-size JPEG stored simultaneously.

Dynamic Range (8.29)

The Sony A900 performed very well in our dynamic range testing, bested only by the Canon 5D Mark II. All of our comparison cameras produced similar results at low ISO settings, but dynamic range inevitably declines as ISO increases, and the Sony and Canon maintained levels above 5 stops out to ISO 1600 and well over 4 stops at ISO 3200, which is a very strong result.

We measure dynamic range — the camera’s ability to capture detail in both the brightest and darkest areas of an image — by repeatedly shooting a standard grayscale chart at multiple ISO settings, under tightly controlled conditions, then feeding the resulting files to Imatest, which combines the results to determine the overall dynamic range.

At ISO 200, the Sony A900 demonstrates an impressive 7.34-stop dynamic range, which falls off at a reasonable rate as ISO settings increase. More on how we test dynamic range.

Only the Nikon D90 outperformed the Sony at ISO 200. Taking results from all official ISO settings into account to produce an overall score, the Canon 5D Mark II is the strongest performer, but the Sony A900 comes in a respectable second.

Image Stabilization (4.71)

The A900 did a decent job of compensating for handshake; we found that with low levels of hand shake, images with the SteadyShot stabilization on were significantly sharper than with it off. However, this was reversed with larger amounts of hand shake; the system made the images slightly less sharp. Most SLRs try and deal with the way your hands shake by moving a small part of the lens, but the A900 takes a different approach; the image sensor is on a moving platform. When the gyroscopes in the camera detect that it is moving because your hands are shaking, this small platform moves to compensate. We test how well a camera deals with hand shake by putting it on a motion control platform, shaking the camera and taking a large number of photos with image stabilization on and off. We also test by moving the camera in both a horizontal (left to right) and vertical (up and down) direction, with two different levels of shake; one low and one high. We then analyze these photos to determine how sharp they are; the better the job the camera does of compensating for the camera movement, the sharper the photos will be. For more details on how this test works, see our How We Test article. More on how we test image stabilization.

Our first test is for a low level of hand shake, such as when you are trying to hold the camera steady with two hands, or braced against a wall. In this situation, the camera only moves a small amount, but there is still more than enough shake to ruin an otherwise perfectly good picture. In this case, the SteadyShot feature of the A900 led to sharper images at all of the shutter speeds that we test at, ranging from 1/500 of a second right down to 1/8 of a second. The only exceptions here were when the camera was moving vertically (up and down); at 1/500 of a second and 1/60 of a second, the SteadyShot system made things slightly worse. But overall, it did a very good job of compensating for the simulated hand shake in this test.

Our next test uses a higher level of shake; about the level you would get if you were trying to take a photo while walking, or while taking a candid shot one-handed. The A900 didn’t do as well here: the larger amount of shake seemed to be more than the SteadyShot system could cope with when the camera was moving horizontally (left to right). On most of the shutter speeds the images taken with SteadyShot on were less sharp than with it turned off, as you can see in the examples below. There was some improvement in sharpness with vertical (up-down) movement, though, but we feel that the horizontal correction is more important,since handshake is more of a left-to-right movement than up-down.

The bottom line here is that we would recommend that you leave SteadyShot turned on in any situation where hand shake is likely to be an issue, as it does a good job of making shots significantly sharper across the range of shutter speeds with small amounts of hand shake. However, like all image stabilization systems, it can’t work miracles, and in situations with larger amounts of shake, it sometimes made things a little worse. So, turn it off if you are running around, but turn it on if you are standing still to take shots.

The A900 didn’t have the problems that the Canon 5D Mark II had with stabilization results worse at some shutter speeds; it made improvements across the entire range. But it’s no slam dunk; we found that the image stabilization of the Nikon D700 produced sharper images at the critical shutter speeds of 1/60 and 1/125 of a second. However, in overall performance, there was not that much difference between the A900 and D700. You should remember, however, that the performance of the 5D Mark II and D700 is dependent on the lens, as the image stabilization on these cameras happens in the lens itself. This means that if you were to use either camera with a different lens, you would probably get very different results.

It is also worth remembering that the two different types of image stabilization have their pros and cons. The sensor approach used by the A900 means that the lens does not require any complex built-in mechanisms, and you’ll get the benefit of image stabilization whatever type of lens you use. This could also mean that the lenses are cheaper as they are easier to make. However, the lens-based image stabilization that cameras like the Canon 5D Mark II and the D700 use means that you can upgrade the image stabilization whenever you buy a new lens, and the lens manufacturers are constantly improving the technology that they use.

Below are stills from some of our test photos taken with the Sony A900, showing an average image from the horizontal test. The target is a slanted line.

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