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White Balance

The SD500 has five white balance presets (sunny, cloudy, incandescent, fluorescent and fluorescent H) in addition to the default auto white balance. There is also a 'custom' white balance setting, which allows you to point the camera at a white or gray object and set the white balance manually. The custom white balance setting is remembered even if you turn the camera off. In normal outdoor shooting the auto white balance works perfectly (as confirmed by our studio tests). Indoors it's a bit more hit and miss, as we've seen with most Canon PowerShots, fluorescent lighting doesn't cause much of a problem, whereas incandescent (tungsten) lighting causes a fairly strong orange color cast. Best to stick to the preset (or one-push custom WB) if you want more neutral colors. We've spoken to Canon about its approach to white balance and have been told that the warm colors we see when shooting under incandescant light are intentional and are intended to 'try to keep some of the warm atmosphere of this kind of shot'. Mmmm.

Outdoor - Auto WB
Red -0.5%, Blue -0.1%
Excellent

Fluorescent - Auto WB
Red 0.1%, Blue -0.5%
Excellent
Incandescent - Auto WB
Red 7.8%, Blue -11.8%
Average

Flash Performance

The SD500's built-in flash has a quoted working range of 0.5m - 4.8m (1.6 - 16.4 ft) at the wide end of the zoom and 0.5m - 2.8m (1.6 - 9.8 ft) at the tele end - slightly more powerful than most other models in the range. It also works down to about 30cm (12 inches) in macro mode (in all cases assuming the ISO is set to auto). In our real-world tests the flash did a decent job with virtually no color cast but a slight tendency to underexpose (which is easy to fix and a lot better than burnt out results) and some issues seemingly connected to the choice of focus point in AiAF mode (see below). The flash is also very fast - even with the red-eye reduction turned on, meaning you won't miss any spur of the moment shots waiting for the flash. We found the AF illuminator would allow focus in complete darkness (or as near as we can get) at distances of up to around 1.0m. In low light the AF illuminator can help focus at distances of up to around 2.0m.

Skin tone
Slight underexposure, excellent color
Color chart
Slight underexposure, excellent color

Macro Focus

As is common to most compact digital cameras the SD500's macro mode is most effective at the wide end of the zoom, where you can get as close as 5cm - not bad at all for an 'ultra-compact'. At the long end of the zoom the performance is less impressive - 30cm subject distance - but still pretty useful. There is inevitably some distortion when shooting very close up at the wide end, but it is not too strong, and certainly less so than many of its competitors.

Wide macro - 52 x 39mm coverage
59 px/mm (1497 px/in)
Distortion: Low to average
Corner softness: Average
Equiv. focal length: 37 mm
Mid Zoom macro - 103 x 77 mm coverage
30 px/mm (756 px/in)
Distortion: Low
Corner softness: Low
Equiv. focal length: 111 mm

Barrel and Pincushion Distortion

Barrel distortion is - at 1.0% - low for a camera in this class, and certainly doesn't mar real world scenic shots. There is virtually no measurable distortion at the telephoto end of the zoom. There is a tiny amount of vignetting (darkening of the corners of the frame) at the widest zoom setting, but didn't see this in real world shots.

Barrel distortion - 1.0% at Wide angle
Equiv. focal length: 37 mm
Pincushion distortion - 0.1% at Telephoto
Equiv. focal length: 111 mm

Noise Comparison

Here for visual comparison are four identical shots taken at 50, 100, 200 and 400 ISO settings in our studio. The exposures are not long enough for Canon's noise reduction to kick in (according to the documentation this happens with shutter speeds of 1.3 seconds and over). ISO 50 is very clean, and ISO 100 and 200 are perfectly usable. ISO 400 has plenty of visible noise, though it is no worse than the majority of the competition, and is better than most 5 megapixel models.

ISO 50 100% crop ISO 100 100% crop
ISO 200 100% crop ISO 400 100% crop

 

Specific Image Quality Issues

Of course all ultra-compact cameras such as this are going to present some kind of compromise when it comes to image quality. The question is how much of a compromise are we prepared to accept in image quality terms to get a camera that is truly pocket-sized, and is there any real advantage to the large 7 megapixel files (over, say the 4 megapixel SD300) in real terms for everyday use?

First the good news; this is a Canon and has all the usual Canon trademarks; excellent, vivid but natural color, very accurate exposure and focus and a surprising amount of detail (see resolution tests). The images - especially those containing fine low contrast detail such as foliage - can look a little soft, or even muddy (they are very smooth, almost too 'polished'), but they respond well to sharpening and print beautifully. Higher contrast detail is rendered very sharply, but very bright, contrasty scenes can play havoc with the metering (see below).

We found corner softness to be a minor problem at the wide end of the zoom/max aperture, but it's a lot better than in previous models, and isn't really visible in real-world shots. We also found the usual Canon Achilles heel, purple fringing, to be a significant problem in most high contrast shots. Ultimately, the SD500 produces the kind of results few of the target market would find anything to complain about, and it would make a perfect 'carry always' camera for anyone who normally uses a bigger, more sophisticated camera and doesn't want to sacrifice too much image quality for the sake of portability. I'd also note that the problems below represent no more than around 5% of the 800 or so shots I took during this test, and - aside from purple fringing - are confined to a relatively narrow band of shooting situations.

Color fringing

Noticeable purple fringing is present to some degree in all shots containing very bright (especially overexposed) areas, and in many shots it's very pronounced. It's not enough to mar shots in most circumstances, but wideangle shots on bright days can produce very strong fringes at the boundaries where bright and dark areas meet. It is considerably worse at the edge of the frame, and - compact point and shoot camera or not - something Canon should be doing more to minimize.

100% crop 37 mm equiv., F2.8

Burnt out highlights/exposure problems

We found that very bright situations sometimes resulted in serious exposure problems (significant over exposure). The dynamic range actually appears to be pretty good, though the default contrast curve seems to be quite steep, meaning you need spot-on exposure to ensure highlight and shadow information are retained. The problem only seems to occur in unusual shooting situations, especially bright, hazy days such as this one.

100% crop 37 mm equiv., F2.8

AiAF multi-point focus errors

The SD500 is certainly fast at focusing, but it also misses more often than it should - though to put it into perspective we're maybe talking 1 shot in a 100 (more in low light). As with all 'intelligent' multi-point AF systems the problem is often the camera choosing a small foreground object to focus on, something you can easily avoid by watching the focus point chosen (or sticking to single point focus). The AiAF system seems incredibly sensitive to tiny changes in the framing of the scene, and is simply too good at finding a small object in the foreground (in fact I'd suggest switching to center AF most of the time).

100% crop 37 mm equiv., F7.1

The rather over-sensitive AiAF system also causes problems with flash exposures. Time after time when shooting across a table I ended up with results like this - perfectly exposed table, very dark people (the actual subject of the shot!). I soon realized this is again a focus error - the flash metering is linked to the focus point, and if you look closely you can see the camera has focused on the foreground, not the people. Again, this can be fixed by switching to centre focus (or of course by careful checking of the focus point selected by the AiAF system).

100% crop 37 mm equiv., F2.8
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