The DIGIC 4 processor is at the heart of all Canon's latest DSLRs. The EOS 500D has one, the EOS 50D has one, as does the EOS 5D MkII. The new EOS-1D MkIV professional camera has two of them, and so does the EOS 7D, so as you can imagine it has some fairly impressive performance figures. It can take a picture within about a quarter of a second of being switched on, and in single shot mode it has effectively zero shutter lag, and can shoot as fast as you can press the shutter until the memory card is full. In continuous shooting mode it is nothing short of astonishing, shooting at 8fps in all quality and size settings including Raw + JPEG mode. The Nikon D300s can manage 8fps, but only with the addition of an external power pack. The 7D's image buffer is big enough, and the data processing fast enough for 126 shots at this speed in JPEG mode, 15 in Raw or 6 in Raw + JPEG.
The 7D features a new autofocus system, which is always a bit of an event for Canon. It is, to say the least, impressive. It has 19 f/2.8 cross-type sensors arranged in a broad diamond pattern across the central area of the frame, which can be used either for a wide area AF mode, in selected groups for small area AF, or singly for point or centre. It is a fantastically adaptable system, and clever too. There is a custom function that allows the selected AF point to rotate if you turn the camera between vertical and horizontal. Whatever the mode, focusing is incredibly fast and reliably accurate, with one exception. In live view mode the camera has the option to use its contrast detection AF system, a rather poor single-zone affair which is both slow and inaccurate. If only Canon could come up with a way to use phase detection AF in live view mode, as Sony has.
You're probably getting the impression by now that I quite like the EOS 7D, but I've saved the best bit until last, because here I mention picture quality. In every respect, the 7D performs brilliantly, coping with low light, high contrast, fast moving subjects and bright colours. I can honestly say I can't remember when I've been more impressed by the results from a camera, except possibly for the EOS 5D MkII, but then I think we all knew that one was going to be good.
In noise control alone the 7D is head and shoulders above almost anything else I've tested including some full-frame cameras, producing usable shots at 6400 ISO, and even the extended 12,800 ISO maximum is far from useless. At lower ISO settings the picture quality is pretty much flawless. One possible concern with such a high resolution APS-C sensor is of course dynamic range, but here too the 7D excels. The standard JPEG results do have some highlight clipping in high-contrast lighting, but it is possible to pull this back by at least half a stop in Raw mode. The 7D has an Auto Lighting Optimiser feature which helps to preserve shadow detail.
All in all I'm massively impressed by the EOS 7D. Canon has set out to make the best APS-C camera on the market, and in my opinion it has succeeded most admirably. Admittedly £1,500 is a lot of money for a camera, but this is the sort of kit you could earn a living with. I would have no qualms about shooting a big wedding using this camera, although I think I'd put a better lens on it. The 18-135mm f/3.5-5.6 EF-S that was supplied with my review camera, and is available as a kit lens for the 7D, is frankly not very good, with significant chromatic aberration and corner vignetting that even the camera's automatic peripheral lighting correction didn't completely cure.
The Canon EOS 7D is without doubt one of the best cameras currently available, offering fantastic build quality, lightning fast performance and superb image quality in virtually any conditions. It is more expensive than its main rivals, but it's worth the extra for a camera this good.