As you'd expect from one of Canon's flagship models, performance is exceptional. The camera starts up in just over one second and shuts down again almost as quickly. In single shot mode it can take a photo roughly every 1.6 seconds, which is about as fast as you can press the shutter button, while in continuous mode it can shoot at approximately one frame every 0.6 seconds, and can apparently keep that up until the memory card is full. Focusing is incredibly fast, in fact in good light it's virtually instant and amazingly reliable. I used the S5 to shoot the British Olympic windsurfing team racing at Weymouth, and in over 120 shots of fast moving subjects at maximum zoom range on an overcast day it only missed the focus once, which is an astonishing performance. It also works well in low light conditions, with an AF assist lamp with a range of several metres. The image stabilisation system is as good as ever, and I was able to take shake-free hand-held shots at maximum zoom and a shutter speed of 1/30th of a second. Battery life will obviously depend on the type of AA cells that you use, but with a set of four 2300mAh Ni-MH batteries I have taken well over 300 shots with no sign of the battery level indicator so far. Image file sizes are large for an 8MP camera, averaging around 4.3MB at maximum quality and resolution, which means very little image compression, but also means that a 1GB SD card is enough for 286 shots.
With all that performance and versatility it would be a shame if the image quality wasn't up to scratch, wouldn't it? Well, to be honest I was a little disappointed, mostly because I had such high expectations. The Canon S5 IS suffers from almost exactly the same problems as the Panasonic FZ18. It has a good lens, superb metering and autofocus, and one of the best image processors on the market, but it is somewhat let down by an inferior sensor. The tiny 1/2.5-in CCD produces good quality images at the minimum ISO setting, with good colour balance and dynamic range, but even at 100 IS0 there was some noise visible, and the 1600 ISO maximum setting was effectively useless. The lens generally performed well, producing little distortion at wide angle, but I was a bit surprised to see chromatic aberration and softness towards the edges of the frame. Don't misunderstand me, the image quality is by no means bad; in fact it's comfortably above average, it's just not as good as I'd hoped.
The Canon PowerShot S5 IS is unquestionably the most versatile digital camera on the market, with a powerful high quality zoom lens, superb image stabilisation, class-leading performance and what may be the best AF system on the market. It has a huge range of features, including a video mode with full zoom lens and stereo audio. It is slightly let down by the small sensor and its inherent noise problems, but it is still an outstanding camera by any standard.