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White Balance

As per our results with the S45 (as well as G3 and G5) Canon's automatic white balance works well under natural light and less so in incandescent or fluorescent lighting. As you can see from the samples below in incandescent light automatic white balance produced a strong orange cast. The pre-programmed presets work well as does manual preset white balance.

Outdoors, Auto Outdoors, Cloudy (or Sunny) Outdoors, Manual
Incandescent, Auto Incandescent, Incandescent Incandescent, Manual
Fluorescent, Auto Fluorescent, Fluorescent (or H) Fluorescent, Manual

Macro Focus

The S50's closest macro performance as at wide angle, however for the best images with the least distortion and corner softness telephoto macro produced only slightly larger frame coverage. The macro tests below are using our new macro focus test chart and measurement system; each line on the grid is 10 mm, taken at shortest subject distance in macro mode.

Wide angle - 94 mm x 71 mm coverage
27 px/mm (686 px/in)
Distortion: High
Corner softness: Average
Telephoto - 112 mm x 84 mm coverage
23 px/mm (584 px/in)
Distortion: None
Corner softness: Low

Flash Performance

The S50's slim internal flash unit has a quoted range of 4 m at wide angle and 2.5 m at telephoto (at ISO 100). Obviously ranges increase if you are shooting in Auto mode (with Auto ISO). Our tests showed good color balance but a little underexposure notably more on our 'normal' skin tone flash shot.

Skin tone - Natural color, no blue cast, slightly underexposed. Color patches - Good color balance, no color cast, slightly underexposed.

Night exposures

The S50 has two methods available for night shots, the scene exposure mode 'Night Scene' and manual exposure. Night Scene is limited to a longest exposure of 1 second (which is honestly fairly useless for night exposures). Thus I chose to use manual exposure mode for the samples below. The S50 has automatic dark frame noise reduction for exposures of 1.3 seconds or longer. Surprisingly there were no visible 'hot pixels' on these exposures, surprising because we did notice some on G5 shots of the same length.

Manual exposure: ISO 50, 4 sec, F4.0
Manual exposure: ISO 50, 15 sec, F8.0

Barrel and Pincushion Distortion

The S50 has the same lens as the S45 and therefore exhibits the same distortion characteristics, that is just under 1.0% barrel distortion at wide angle and no measurable pincushion distortion at full telephoto. This is a good performance for a compact extending digital camera lens.

Barrel Distortion, 0.9% @ wide angle Pincushion Distortion, 0% @ telephoto

Vignetting / Light fall off

Our vignetting / light fall off test is very simple, a shot of a blank wall from two meters away, vignetting will always be most visible at wide angle and maximum aperture and will start to disappear at smaller apertures and/or further zoom. Just like the S45 the S50 exhibits some visible vignetting at full wide angle and maximum aperture but this soon disappears with smaller apertures or more zoom.

Some corner vignetting visible at wide angle and maximum aperture (F2.8) No noticeable vignetting at telephoto (F4.9)

Purple Fringing (Chromatic Aberrations)

As we noted with the G5 the introduction of the five megapixel sensor has affected the S50's chromatic aberration performance. Purple fringing is fairly strong, especially at maximum aperture and/or wide angle. I was quite disappointed (but not that surprised) to see this extra fringing and must hold it into consideration when producing my overall conclusion.

Fringing visible around contrast, F2.8 Our standard chromatic aberration test shot

Overall Image Quality / Specific Issues

As with the upgrade of the G3's system to the G5 the S45 to S50 decision probably wasn't a difficult one for Canon to make, upgrade the sensor and a few other components, change the body color and labeling (perhaps there was a little more to it than this). And while the S50 performs well as a compact five megapixel three times zoom compact camera I simply don't feel it is as good at that as the S45 was with the four megapixel sensor. It seems to me that with these very small lens systems there is an optimum sensor resolution beyond which problems such as sharpness and chromatic aberrations increase. Add to this the fact that we are seeing more noise from the 1/1.8" type five megapixel CCD and you may begin to understand some of my reasoning.

Shallow angle jaggies

Noted in our G5 review and confirmed on the S50 (another five megapixel Canon with the same processing engine). At very shallow angles (approximately ten degrees or less) in a strong contrast the camera's algorithms (either demosaic or sharpening) don't alias the diagonal line particularly well and it can end up looking slightly jagged.

Rotated CCD

Theory: If you use a digital camera to take a picture of itself in a mirror the camera will always appear horizontal in the final image. Well, not if the sensor isn't level it won't. Something I noted very early on with our loan S50 was that the sensor was not aligned to horizontal, this meant that during testing I always had to adjust the tripod head until the image on the LCD 'appeared' level rather than trusting the spirit level on the tripod shoe. Canon's response was that this was unavoidable in a mass production environment (I personally haven't noticed it to this extent before).

Canon S50: 1.1° Canon A70: 0°
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