Sony Alpha A900

Color (11.00)

In our tests for color accuracy, the Sony A900 was an unimpressive performer compared with other high-end digital SLRs. When set to the color mode that has the least impact on accurate color reproduction, the A900 still had problems reproducing yellow and green values well, and the blues and purples also showed a noticeable color shift. Skin tone reproduction, on the other hand, was quite precise.

Sony gets credit for offering multiple settings to tailor color reproduction to the subject at hand, in the form of Creative Styles (details below). There are 13 of them in all, ranging from the unobtrusive Neutral and Clear to the more aggressive Sunset and Vivid modes. For our color accuracy tests we first shot the X-Rite ColorChecker chart in each available color mode, then analyzed the resulting images using Imatest to determine the setting that produces the lowest color error. That’s the mode we use for comparison purposes — for the A900, it turned out to be the Neutral Creative Style. Overall, this produced a color shift of 5.92 and a notable undersaturation at 90.28%. Of course, an undersaturated image offers a little extra flexibility when making adjustments with image editing software, but the color shift is problematic. More on how we test color.

In the chart below we compare actual-size crops from photos of the eighteen color squares on the X-Rite ColorChecker chart taken with five cameras, using the most accurate color setting for each. The leftmost column shows the ideal color values from the original chart.

Camera Color Comparisons					Expand
	Ideal	Sony Alpha A900	Canon EOS 5D Mark II	Canon EOS 50D	Nikon D90	Nikon D700
Dark Skin
Light Skin
Blue Sky
Foliage
Blue Flower
Bluish Green
	Ideal	Sony Alpha A900	Canon EOS 5D Mark II	Canon EOS 50D	Nikon D90	Nikon D700
Orange
Purplish Blue
Moderate Red
Purple
Yellow Green
Orange Yellow
	Ideal	Sony Alpha A900	Canon EOS 5D Mark II	Canon EOS 50D	Nikon D90	Nikon D700
Blue
Green
Red
Yellow
Magenta
Cyan

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 chart below compares overall color scores for each of our comparison cameras. The Sony A900 comes up notably short against the others, with the Canon 5D Mark II offering the best results.

Color Modes (5.00)

The Sony A900 offers a Creative Styles feature that tweaks color reproduction to favor the subject at hand. Contrast, saturation, sharpness and brightness are also affected by the choice of Creative Style. You’ll find a full discussion of this feature in the Picture Effects section below, in addition to sample images shot at each setting. Here we’ve chosen five of the most useful options from the thirteen Creative Styles provided and prepared actual-size crops of each color patch taken from photos of the X-Rite ColorChecker chart shot in each mode, for comparison purposes.

As expected in a professional-grade SLR, the Sony A900 supports both the sRGB and Adobe RGB color spaces, the latter useful mainly for commercial printing applications.

Color Mode Comparisons						Expand
	Ideal	Neutral	Standard	Vivid	Portrait	Landscape
Dark Skin
Light Skin
Blue Sky
Foliage
Blue Flower
Bluish Green
	Ideal	Neutral	Standard	Vivid	Portrait	Landscape
Orange
Purplish Blue
Moderate Red
Purple
Yellow Green
Orange Yellow
	Ideal	Neutral	Standard	Vivid	Portrait	Landscape
Blue
Green
Red
Yellow
Magenta
Cyan

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.

White Balance (10.53)

More on how we test color.

Automatic White Balance (10.3)

The automatic white balance setting produced exceptionally accurate results when shooting under daylight illumination, and also scored well when shooting under fluorescent light. The problem arose under incandescent lights, which produced images that were distinctly over-warm. On balance, though, the A900 scored well here.

Custom White Balance (10.75)

Taking a custom white balance reading effectively solved the problem we’d experienced when shooting under incandescent lights using the automatic white balance system. There were color accuracy improvements under fluorescent and daylight illumination as well, but these were already quite close to ideal values under auto white balance.

Shooting under daylight illumination using auto white balance, all of the cameras produced slightly cool results, though the offsets from the ideal for the Sony A900 and Nikon D700 are trivial.

There is a grim consistency to the inability of automatic white balance systems to cope adequately with incandescent lighting which, considering that’s still the source of most household illumination, is profoundly not a good thing. The warming trend is less severe for the Sony A900 than for most of the competition, as shown below, though there’s still an uncomfortable orange hue to the images shot on auto.

It’s interesting that both Sony and Nikon warm up their images when shooting on auto under fluorescents, while Canon errs in the cooler direction, but not enough that you’d notice without a lab at your disposal.

Taking both automatic and custom white balance accuracy into account, the Sony produces acceptable but not impressive overall results when compared to the other cameras in our roundup. The tests are conducted using a controlled lighting system that produces consistent color temperatures for each illumination setting. Images are analyzed using Imatest, which compares the captured colors to the ideal values from the X-Rite color chart.

White Balance Options (7.50)

White balance controls are extensive, if sometimes quirky. In addition to the inevitable auto white balance control, there are six presets, as listed below. Each of these presets can the be fine-tuned to three values above or three values below the default setting. Unfiortunately, there’s no clear indication of what effect these fine-tuning maneuvers have on the picture you’re taking. A deep dive into the manual turns up the fact that each increment represents 10 Mired. A knowledge of photographic science tells you that the higher the Mired number, the higher the color temperature, but this is all getting a bit obscure. On other high-end cameras with white balance fine-tuning, such as the Canon 5D Mark II, you work with s a visual representation of the color space, moving along the blue-amber and magenta-green axes. This is a more straightforward, comprehensible approach.

Setting a custom white balance is simple enough, and there are three slots to store readings if you want to return to them later. You can also enter the white balance adjustment in degrees Kelvin, or enter the value of a green or magenta color compensation filter, between G9 and M9, with each increment approximately equal to CC filter number 5.

Long Exposure (10.68)

In our long exposure testing, which evaluates both color accuracy and image noise performance at shutter speeds from 1 second to 30 seconds, the Sony A900 scored very well, coming in second only to the Nikon D700 in our comparison group.The camera handled both tests with good results, maintaining a color error below 4 until the camera tipped into overexposure at the 30-second exposure, and average noise well below 1% across the board.

Dropping the lights in our lab down to a level found in a darkened room (20 lux, which is barely bright enough to read by), we set the camera to ISO 400 and shoot the X-Rite test chart at a range of exposure times, from 1 second to 30 seconds. These images are then analyzed using Imatest to measure image noise and color accuracy; for cameras offering long-exposure noise reduction, we run the test twice, with this function on and off.

Both color error and saturation changed very little between shutter speeds when shooting with the Sony A900 until we reached a 30-second exposure, when the shots were overexposed even with the aperture fully stopped down. More on how we test long exposure.

Long-exposure noise reduction seems like a great idea, but it is minimally effective in most of our tests, and sometimes actually makes matters worse. This was the case with the Sony A900; except at the slowest shutter speed, long exposure noise measured higher with noise reduction on, by as much as 20%. The explanation for this counterintutive result? Image noise is by its nature random. Long-exposure noise reduction systems attempt to recreate the noise in the original image by taking a second, shutter-closed exposure and then removing the noise found in the black exposure from the original. Problem is, removing random bits can quite logically do more harm than good.

As shown below, the Sony A900 and Nikon D700 produced substantially superior scores in this test, while the other full-frame camera in the field, the Canon 5D Mark II, scored slightly lower than even the APS-C sensor Canon 50D and Nikon D90.