In terms of performance the SX100 IS is well up to Canon's usual high standard. Start-up time is just over two seconds, which is pretty quick considering the size of the lens. In single-shot mode the shot-to-shot cycle time is also just over two seconds, and in continuous shooting it can manage a consistent 1.3 seconds per shot, or 1.5 seconds per shot if it has to focus. The flash is also reasonably quick, taking approximately nine seconds to recharge after a typical shot. Flash frame coverage is excellent, and the higher position of the pop-up flash reduces the likelihood of red-eye, although there is a facility in playback mode to correct it anyway. One of the selling points of the SX100 IS is its movie mode, but in truth this is nothing special. It can shoot at VGA (640 x 480) resolution at 30fps, and as is usually the case the zoom lens cannot be used in video mode. It does have a "compact" mode, which compresses the video do give extra shooting time. In this mode a 1GB memory card is enough for nearly two hours of shooting, but the quality is a bit ropey. In normal still shooting mode, at maximum quality the same 1GB card is enough for 286 shots.
One concern is battery life. Two AA batteries isn't a lot of power for a camera of this size and specification, especially one with a big image stabilised lens. Canon claims 140 shots, and I was able to take at least this many using the standard alkaline batteries supplied with the camera, but the red battery warning started flashing after only about 70 shots. 140 shots isn't much by recent standards, and is less than half the duration of the Fuji S5700 (and presumably the S5800) with its 4x AA power source.
Autofocus is also a usual Canon strong point, and indeed the SX100's AF system is very good. It focuses quickly and accurately in almost any lighting conditions, and seems to be very good at capturing moving objects. Focusing in darkness is aided by a powerful AF assist lamp with a range of approximately 4m.
Canon's optical image stabilisation system is widely regarded as one of the best on the market, and it proves its worth here once again, allowing sharp hand-held shots at least three stops slower than would otherwise be possible.
The SX100 also score high marks for its overall picture quality, although it isn't entirely problem-free. The lens is extremely good, providing almost no barrel distortion at wide angle and only a tiny amount of pincushion distortion at telephoto. The sharpness and level of fine detail is excellent in the centre of the frame, but it does drop off somewhat towards the edges, with some noticeable chromatic aberration. Colour and exposure are also excellent, and the dynamic range of the 1/2.5-inch CCD is surprisingly good, providing both highlight and shadow detail on high-contrast shots. The only real problem is image noise, which is present in all shots over 100 ISO, with 800 ISO and the maximum 1600 ISO being particularly bad. This is odd, since high-ISO capability is another advertised feature of the camera. All in all however, the SX100 IS is an impressive camera for the money, even if its weight and bulk will mean it gets used less often than it should.
For a relatively modest price the Canon PowerShot SX100 IS offers a good range of features to accommodate both novice and more experienced photographers. Its long zoom range gives it added versatility, and its fast performance, superb AF system and high image quality are capable of producing excellent results in a wide range of situations. Its only disadvantages are its bulk and weight, and its poor high-ISO noise reduction.