Sony Alpha A900

	Color Summary
• Color accuracy results under standard illumination poor compared to other digital SLRs • Creative Styles capability offers decent variety of customized color mode settings • Long-exposure color and noise performance very good; only Nikon D700 scored higher
	Product Tour	Page 3 of 18	Noise

Color Accuracy (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. Skintone 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.

Color Chart Comparisons
Sony A900	Canon 5D Mark II	Canon 50D	Nikon D90	Nikon D700
Neutral Mode	Neutral Mode	Faithful Mode	Neutral Mode	Neutral Mode

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
	Ideal	Sony A900	Canon 5D Mark II	Canon 50D	Nikon D90	Nikon D700
Dark Skin
Light Skin
Blue Sky
	Ideal	Sony A900	Canon 5D Mark II	Canon 50D	Nikon D90	Nikon D700
Foliage
Blue Flower
Bluish Green
	Ideal	Sony A900	Canon 5D Mark II	Canon 50D	Nikon D90	Nikon D700
Orange
Purplish Blue
Moderate Red
	Ideal	Sony A900	Canon 5D Mark II	Canon 50D	Nikon D90	Nikon D700
Purple
Yellow Green
Orange Yellow
	Ideal	Sony A900	Canon 5D Mark II	Canon 50D	Nikon D90	Nikon D700
Blue
Green
Red
	Ideal	Sony A900	Canon 5D Mark II	Canon 50D	Nikon D90	Nikon D700
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 Score Comparisons

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.

	Color Mode Comparisons
	Ideal Color: The actual color as displayed on the X-Rite chart.	Neutral: The most accurate color mode based on our tests.	Standard:  The default, offering "rich gradation and beautiful colors," according to Sony.	Vivid: Boosts saturation and contrast, useful for flowers, greenery, blue sky, ocean views.	Portrait: For capturing the skin color in a soft tone," according to Sony.	Landscape: Boosts saturation, contrast and sharpness.
Dark Skin
Light Skin
Blue Sky
	Ideal	Neutral	Standard	Vivid	Portrait	Landscape
Foliage
Blue Flower
Bluish Green
	Ideal	Neutral	Standard	Vivid	Portrait	Landscape
Orange
Purplish Blue
Moderate Red
	Ideal	Neutral	Standard	Vivid	Portrait	Landscape
Purple
Yellow Green
Orange Yellow
	Ideal	Neutral	Standard	Vivid	Portrait	Landscape
Blue
Green
Red
	Ideal	Neutral	Standard	Vivid	Portrait	Landscape
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.

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.

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.

Sony A900 Long Exposure Color Error

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.

Sony A900 Long Exposure Noise

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.

Long Exposure Score Comparison