Sony SLT-A55 Digital Camera Review$899.99
We found that the SLT-A55 captured pretty accurate color, although it struggled with some colors, such as the purples and magenta of our test chart. We also found that the colors were a little oversaturated in all of the color modes that the camera offers, with saturation ranging from 105 per cent up to 120 per cent, which produces almost cartoon-like results. More on how we test color.
To test color accuracy, we shoot our test chart in all of the color modes that the camera offers, and then determine which mode produces the most accurate color. For this camera, this was the Standard mode, but you should remember that color can be a rather subjective thing: some users might prefer the more saturated colors of another mode. You can see how the different modes affect the same colors from our chart in the next section of this review.
NOTE: Because of the way computer monitors reproduce colors, the images above do not exactly match the originals found on the chart or in the captured images. The chart should be used to judge the relative color shift, not the absolute captured colors.
The SLT-A55 offers 6 color modes: Standard, Sunset, Vivid, Portrait, Black & White and Landscape. The differences between these are mostly subtle, but do what you would expect, with Vivid and Sunset boosting the saturation to around 120 per cent and Portrait producing a more muted look than others. Examples from our color test chart for 5 of these modes are shown below.
White balance is a critical factor for camera performance, as a camera has to be able to judge the white balance to show colors correctly. We found that the SLT-A55 did a pretty good job here, judging the white balance of various light sources on auto and correctly setting the white balance when using a custom setting. Like most cameras, the auto setting was slightly confused by incandescent lighting, though.
Automatic White Balance ()
To test the auto setting of the SLT-A55, we took photos of a colorcheck chart under three different types of light: incandescent, fluorescent and simulated daylight. This camera did a very decent job here, getting very close to spot on for the fluorescent and daylight. It was slightly off with the incandescent light, but most camera struggle with this light source.
Custom White Balance ()
We expect that using the custom white balance feature of a camera will produce more accurate results, because we give the camera a white card to work from. We found that the SLT-A55 was a little off here, though: both the incandescent and fluorescent light sources produced a significant error that could be visible in images.
Given this error, If getting a correct white balance is critical to you (such as for product photos, where the images have the match the subject), you might be better off shooting in RAW format and color correcting afterward in Photoshop.
White Balance Options
A good selection of white balance settings are on offer. As well as the full auto mode, there are 6 presets, all of which can be tweaked up or down to three steps (each step represents 10 Mired). You can also enter a color temperature directly, or use the custom setting to measure a white object. 3 memory spots are also available if you are able to visit a location before shooting and check the lighting. The color filter option allows you to set the white balance as a spot on a green/magenta compensation graph. And if you don't know what that means, you will probably never need it.
Shooting in low light often involves using long exposures, and long exposures mean more time for electronic noise to gather in the sensor. This means noisy images, so we test how well the camera deals with this by shooting a number of images at different shutter speeds and examining the noise in them using Imatest. We found that the SLT-A55 had some issues here: although the colors in log exposure images were pretty constant, the noise in images with exposure times of more than 1 second was significant. We also found that enabling the long exposure noise reduction didn't make that much difference: in some cases, it seemed to make things a little worse. More on how we test long exposure.
When we look at the noise in images (see the chart below), we see that the noise in images rises as the exposure time increases, rising from 1.05 per cent to about 1.24 per cent at 30 seconds. The long exposure noise reduction didn't make much difference, and at some speeds it seemed to make things slightly worse.
Compared to other SLRs, the SLT-A55 didn't fare well: many other SLRs have lower, or more consistent, noise with long exposure levels. So, the SLT-A55 earns a lower noise score than all of our comparison cameras.