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White Balance

The W7 offers only the most basic of control over white balance - aside from the default auto setting there are only five presets (flash, tungsten, fluorescent, cloudy and daylight). There is no 'manual' or custom white balance. Although the W7 struggled under tungsten lighting when shooting our test chart it did a marginally better job with fluorescents. In real world use we found auto white balance to be consistently reliable when shooting outdoors and pretty good in mixed lighting (as long as it's fairly bright). It also does better shooting under fluorescents than our test chart would indicate. Under tungsten (incandescent) lighting the results broadly reflect what our test chart shows - all exhibit a warm (or at times downright orange) color cast, which disappears altogether if you switch to the tungsten white balance preset.

Outdoor - Auto WB
Red -0.1%, Blue -0.1%
Excellent

Fluorescent - Auto WB
Red 4.0%, Blue -3.8%
Average
Incandescent - Auto WB
Red 14.3%, Blue -23.2%
Poor

Flash Performance

Flash hasn't traditionally been Sony's strong point, and the unit on the W7 is usable, rather than outstanding. On the positive side, the color is almost perfect and the output is throttled down well when shooting nearby subjects, meaning blown-out results are rare. The red-eye reduction mode is as effective as a pre-flash can be, but the delay it adds between pressing the shutter and the picture being taken is unacceptable.

Skin tone
Good color, good exposure
Color chart
Excellent color, very slight under exposure

Macro Focus

The W7 has a dedicated macro mode that works at all focal lengths, but - as is normal in cameras such as this - is most effective towards the wide end of the zoom. It's not the most impressive macro mode we've ever seen, with a minimum focus distance of around 6cm giving you an area of around 60mm across to work with, but focus is very reliable. Inevitably there is some distortion at the wide end of the zoom, and noticeable corner softness, though it's not as strong as some of the W7's competitors (mainly I suspect due to the fact it doesn't focus as closely).

Wide macro - 60 x 45 coverage
51 px/mm (1283 px/in)
Distortion: Low to average
Corner softness: Average
Equiv. focal length: 38 mm
Tele macro - 91 x 68 coverage
34 px/mm (857 px/in)
Distortion: Low to average
Corner softness: Above average
Equiv. focal length: 114 mm

Barrel and Pincushion Distortion

Whilst there is measurable distortion at the wide end of the zoom (around 1.2%), it is no worse than most ultra-compact 3x zooms. It certainly doesn't have a significant impact on real-world shots. Edge sharpness leaves a little to be desired, though it does improve as focus distance and/or aperture increases (these are shot at F2.8). There is no measurable pincushion distortion at the long (114mm equiv.) end of the zoom range.

Barrel distortion - 1.2% at Wide angle
Equiv. focal length: 38 mm
Barrel distortion - 0.0% at Telephoto
Equiv. focal length: 114 mm

Noise Comparison

Here for visual comparison are three identical shots taken at 100, 200 and 400 ISO settings in our studio. Sony's noise reduction is fairly harsh, but it does produce very smooth-looking results even at ISO 400. There's no doubt that ISO 100 and 200 are perfectly usable, and that the ISO 400 setting is fine as long as you're not intending to print too large (the 7MP Sony CCD has surprisingly low noise considering its tiny pixel size). You can see some loss of fine, low contrast detail (such as foliage) at even the ISO 100 setting, which - given the resolution of the lens/sensor, we can only put down to noise reduction. It's a pity Sony didn't include an ISO 50 setting in its Cyber-shot range, as this would allow for less noise reduction and sharper images in good light.

ISO 100 100% crop ISO 200 100% crop
 
ISO 400 100% crop  

Specific Image Quality Issues

Very little to complain about here, certainly as far as the target market is concerned. Color is excellent; vibrant without being artificial, focus accuracy - even in low light - is excellent, and the noise levels are low. Exposure is almost 100% reliable (only giving minor problems in scenes with extremely high contrast, and even then rarely), and dynamic range seems good even given the fairly high default contrast. The images are not going to impress purists - they're a little 'over processed', but for the 'point-and-shoot' crowd producing prints at 5x7 inches or less they look great. We did have some problems with missed focus at the long end of the zoom, and there is mild corner softness in some shots, but overall nothing too painful for a camera at this price point.

Color fringing

Purple fringing is thankfully fairly rare, and tends only to occur at the edges of areas of over-exposure, such as this window, or in some cases when shooting foliage against a bright sky. It's most common at the wide end of the lens, and cannot be considered a major issue.

100% crop 39 mm equiv., F2.8

Dynamic Range/Highlight clipping

As is usually the case with Sony Cyber-shot cameras, the processing tends to clip highlights rather sharply, which in high contrast situations (with a wide range of brightness levels from deep shadows to bright highlights) tends to burn out the brightest parts of the scene. This is exacerbated by a tendency to meter for the shadows in such scenes, something you can at least avoid by the careful use of AE compensation or manual exposure. We found this extreme highlight clipping (as seen below) to be a problem in no more than about 5% of our 500 or so outdoor gallery shots.

100% crop 39 mm equiv., F2.8
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