Some thoughts about buying a Digital Camera

1) Make sure it has rechargeable batteries (most do).
Even if you buy top quality batteries, you will get through an awful lot and it will become very expensive. Depending on how keen you are on photography, it might also be a good idea to buy a spare rechargeable and carry it in your pocket. I bought a brand new one for my Canon, list price over £70, for around £30 on Ebay. It's not a Canon make, but works just as well.

2) Only choose an optical zoom.
Digital zooms work by magnifying the middle of the sensor. It is not a proper zoom, and the effect is similar to zooming in on a computer and seeing the image become 'blocky.' No extra information is added, and you might as well do it better on the computer. An optical zoom still uses the whole area of the sensor so that all the pixels are used for the image, not just the centre few. Result - much better quality. A digital zoom can make a 5Mp camera become a 1Mp camera. However, if you just intend to take the camera to have small prints produced it could be useful, though you can usually zoom in on the printing machine.

3) Don't be carried away by megapixels!
The sensor in a digital camera is very small. The Canon Powershot 5500 (5Mp) has a sensor size of 7.2 x 5.3 mm. The Konica Minolta Dimage A2 (8Mp) has a sensor size of 8.8 x 6.6 mm. Imagine trying to produce a sensor of this kind of size holding 14 million picture cells. Not only would it be phenominally expensive to produce, but it would actually be beyond the resolving power of the lenses. Leica, renowned for their high-quality lenses, are just about to bring out the M8, the first true interchangeable-lens, manual rangefinder digital. This (£3000 without a lens) only has a 10Mp sensor, as the quality would decline with more. While film is flat, digital sensors have depth for each pixel so that the light from the lens does not hit them straight on. Therefore at the edge of the frame there is chromatic aberration (shown by coloured edges) and vignetting (shown by darkening at the edges and the corners). There are some examples below.

4) It depends what you want it for.
If you just want a decent camera for normal-sized 'enprints' then get a compact, with a decent optical zoom, and around 5Mp. I remember Roger Hicks in Amateur Photographer magazine talking about someone who bought an expensive Leica and complaining that his prints were actually no better that those from any other camera. It turned out that he was having them printed to enprint size at the local High Street processor! There is no point buying an expensive camera if the prints will not be enlarged beyond this.

There is more, however. If you want to take good pictures of any sport other than chess, an SLR is probably essential. Entry-level ones (still better than a compact) start at about £400.

If you see photography as a particular hobby or interest, go for an SLR. My own favourite camera is the Olympus, though it is something of a niche product with few independent lenses. The other main makes are Canon and Nikon.