As we've come to expect from Canon's Ixus family of cameras, the 850 IS is beautifully constructed. You'll keep noticing little details long after it's been unpacked.
The only slight blemish on the otherwise sumptuous exterior is the rather flimsy battery/SD card slot cover. That minor grumble aside, the Canon feels as good as it looks, with a decent, comfortable grip.
The 7.1Mp (megapixel) sensor is capable of providing images a shade over 3,000 pixels across, or movies at a TV-friendly 640x480. As well as good resolution, the 850 benefits from a lens upgrade, with a healthy f2.8-5.8 aperture spread and an unusually wide 28-105mm 35mm equivalent range from the 3.8x optical zoom.
The 850 features integrated optical image stabilisation (hence the 'IS' in the name), permitting the use of slower shutter speeds when things turn murky. If that's not enough, the 850 can raise the ISO to a maximum of 1,600, beyond the range of most compacts and into realms inhabited by digital SLR (single-lens reflex) cameras.
Like the Fujifilm reviewed last month, the Canon incorporates a 'face detection' system, which increasingly seems like the new must-have feature. The Canon cleverly identifies a person's face in-shot, and sets the exposure and focusing accordingly.
In true Ixus style, the Canon doesn't offer much in the way of manual exposure control, instead offering only white balance, ISO, metering and exposure compensation tweaking. But for automatic use, needs are well met with a wealth of scene modes.
Image quality overall is really very good, with mostly accurate exposures and plenty of detail. As with a lot of Canons, though, the automatic white balance tends to favour slightly warmer tones if left unguided. The noise on higher ISOs becomes problematic – we hit trouble beyond about 400 – but at lower levels images are impressively clean.