Sony Alpha A900

	White Balance Summary
• Auto white balance performed very well with fluorescent and daylight illumination, but had problems with incandescent lights • Custom white balance solves the incandescent problem, produces highly accurate results • Six white balance presets provided • Direct entry of degrees Kelvin and color filter equivalents supported
	Resolution	Page 6 of 18	Sample Photos

Automatic White Balance (10.30)

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.

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.

Auto Daylight White Balance Performance Comparison

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.

Auto Incandescent White Balance Performance Comparison

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.

Auto Fluorescent White Balance Performance Comparison

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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.

Sony A900 Custom White Balance

White Balance (10.53)

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 Score Comparison

White Balance Settings (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.

White Balance Types
Display	Mode	Color Temperature
	Daylight	approx. 5300K
	Shade	approx. 7500K
	Cloudy	approx. 6100K
	Tungsten	approx. 2800K
	Fluorescent	not provided
	Flash	approx. 6500K
	Custom	user setting
	Kelvin	user setting
	Color Filter	user setting