The Canon S90 is the latest compact DSLR replacement from Canon - the little brother to the successful Canon G11.

Profits are squeezed to the point of asphyxiation in the compact camera market at the moment; tough economic times mean your typical 'point and shoot' compact owner doesn't feel the urge to upgrade as often as makers would like.

There's also a bewildering range of new cameras to choose from. And of course, camera phones keep getting better and better.

Hence the rebranding of some compacts as 'SLR backups'. The term's a bit vague, but basically it refers to a compact camera which offers better optical quality and more sophisticated imaging options than your typical point-and-clicker - while still being very compact and easy to carry around.

The kind of compact, in other words, that SLR owners would be happy to take as a backup, or use as their main camera when the SLR is just too big and indiscrete.

The Canon PowerShot S90 certainly falls into this category. It weighs in at a slimline 175g and is only about three inches deep with its 28-105mm lens fully extended.

canon powershot s90

At the same time, it shoots in RAW as well as JPEG and comes with Canon's Digital Photo Professional RAW-processing software, just as you get with Canon EOS SLRs. As well as SLRs, the Canon PowerShot S90 has a lot in common with Canon's flagship compact, the PowerShot G11.

You get the same 10-megapixel sensor, for instance, which as well as offering a very respectful resolution, does a sterling job of keeping digital noise down at higher ISO settings.

And while the Canon PowerShot S90 only has a 3.8x optical zoom lens compared to the 5x zoom on the PowerShot G11, the difference is not that huge.