Given its small LCD and limited zoom range -- a digital camera's display and zoom generally consume the most power -- you'd think that the S70 would have exemplary battery life. Not so. Its 720mAh lithium-ion battery barely eked out 226 shots and one movie clip before dying. A second test finessed that up to 262 shots but with only 38 percent of those using the flash (we usually aim for 50 percent). That may sound like a lot, but you'll probably get worse battery performance in real-world usage, and a camera in its class should be able to sustain power for at least 500 shots.
The zoom operates a bit slowly and frequently overshoots a bit before snapping into one of its predefined increments. It's also fairly noisy. Once you have your scene framed, however, it focuses relatively quickly. There's a bit of barrel distortion at the widest-angle zoom but no more than we've seen with other cameras. As with other cameras, when using manual focus, a magnified view of the subject appears on the LCD. However, it's very difficult to judge focus on the small but otherwise bright and sharp display. At least the display reveals almost 100 percent of the scene; the optical viewfinder shows only 80 percent.
In general, the Canon PowerShot S70 takes excellent photos, properly exposed and sharp, with neutral, accurate colours. At the camera's best light-sensitivity setting, ISO 50, the photos display very little noise; at ISO 100, there's a bit more but not enough to seriously impact the overall image quality. At ISO 200 and 400, however, the noise became obtrusive.
Unlike its sibling, the S60, which uses the same lens but a different sensor, the S70 exhibited minimal purple fringing. However, the lens's sharpness falls off toward the left side of the scene, which means that high-contrast edges in the upper-left corner become a potential trouble spot for fringing.
With manual white balance, the S70 produces very neutral grays. And using the tungsten white-balance preset in our test scene yielded fairly neutral, if slightly cool, results. The auto white balance works fairly well in natural light, but as usual with Canon cameras, the S70 delivered very orange images under tungsten lights.
Additional editing by: Guy Cocker