The G-series cameras have always had exceptionally good overall performance, and the G9 is no exception. It starts up extremely quickly in just over 1.2 seconds, and shuts down again in under two seconds. In single-shot mode and the highest quality JPEG setting it averages 2.2 seconds per shot, but the real surprise is that shooting in RAW mode barely slows it down at all, averaging 2.6 seconds per shot in RAW+JPEG mode. In standard continuous shooting mode it can maintain an impressive 0.6 seconds per frame, while in the continuous AF mode it manages one shot per second. The AF system, always a Canon strongpoint, is impressively fast and reliable, and operates well even in very low light conditions, although as usual the AiAF wide-area mode is rather hit-or-miss, frequently focusing on the background of a scene and missing the foreground subject. A blindingly bright pattern-projecting AF assist lamp (which I think may actually be a diode laser rather than an LED) means it can focus in total darkness at a range of about five metres. The G9 features Canon's excellent optical image stabilisation system, and it works extremely well. I had no problem at all shooting hand-held at shutter speeds of 1/15th of a second. One feature that doesn't perform quite as well however is the zoom control. It is stepped with 13 increments between the longest and shortest ends, but the control is rather jerky and imprecise.
Finally we come to the crucial issue of image quality, and here there is good news and bad. The good news is that the image quality at its best is superb. At the lowest ISO setting, JPEG images are pin-sharp and virtually noise free, and shooting in RAW mode produces even better results. The overall level of detail is fantastic, significantly better than any of the other 12MP compacts I've reviewed so far. In top quality mode the G9 produces very large JPEG files averaging around 6.5MB, the largest I've seen from a compact camera, and virtually uncompressed. The lens is also superb, with excellent edge-to-edge sharpness and producing very little distortion at either end of the zoom range. The bad news is that the G9 suffers from exactly the same problems as all the other super-powerful compact cameras: limited dynamic range and image noise problems at even relatively low ISO settings. Although the DIGIC III processor and the very accurate metering system do their best, and it is far from the worst result I've seen, high-contrast images do suffer from murky shadows and clipped highlights. Noise is visible in the darker areas of shots at 100 ISO, and causes problems with colour rendition at 200. This isn't a disappointing result, and the G9 is capable of producing superb image quality, but it isn't as good as it could have been. The same camera with a larger or lower-powered sensor could have been even better, but as usual the marketing department has had its way and the bigger numbers have won the day.
With superb build quality, a huge range of features and options, fast performance and - at its best - outstanding image quality, the Canon PowerShot G9 is certainly one of the best compact cameras on the market, and a very good creative tool for the enthusiast photographer. However it does suffer from the usual limited dynamic range and noise problems of super-powerful compacts, and considering it is nearly the price of an entry-level DSLR, one has to ask if it's really worth the money.