Early digital cameras used to eat batteries as a pre-breakfast snack. Current models are less greedy, but it's worth choosing a camera that enjoys a varied diet. Some take AA batteries - rechargeable or otherwise - while others use proprietary rechargeable battery packs, and most will run off an AC adaptor.

Ideally you want all three options, so you can switch to standard AA's when the rechargeable gives up at the top of Mount Kilimanjaro. The AC adaptor comes in handy when you return home and want to transfer the pictures onto your computer without depleting the last of the battery.

I spy with my Electronic Eye

The most important elements of a digital camera are the ones you can't assess by reading the back of the box. The quality of the lens, CCD and compression software make the difference between sharp, colorful pictures and leaden mash, but there's no easy way to find out how well a particular model can see. Don't rely on a single review. Performance depends on the subjects chosen and look for sample images depicting the kinds of things you might photograph. Cameras that do well outside don't always excel at indoor close-ups, and vice versa.

An LCD viewfinder/review screen that enables you to see your pictures straight away is an asset, but you also want an optical viewfinder for sunny days when your batteries are running low. Macro modes can bring you within a few inches of your subject - much closer than you'd get with a conventional snapshot camera - while zoom lenses keep you safely away from the safari park tigers. Make sure you're getting an optical zoom, because the digital ones don't do anything you couldn't do on your computer later on. Rotating lenses are a bit of a gimmick unless you're incredibly keen on self portraits. 

Unprocessed images are much larger than an affordable memory card can accommodate in reasonable numbers, so the files have to be compressed. Better cameras offer several levels of squish, enabling you to save a handful of good looking images, or a lot that have been stomped on really hard. If you're going the megapixel route, it's worth choosing a camera that can change down to 800x600 when you want snapshots for the web.

From Here to There

Although it's usually possible to connect your camera directly to a television, and sometimes to a printer, you'll generally want to transfer the image on to your computer. Your camera should come with suitable software, and these days some of it actually works quite well.

Many cameras also come with TWAIN drivers that enable you to load snapshots directly into image editing applications such as Adobe Photoshop and Paint Shop Pro. If you don't have either of these programs, don't panic, because you'll almost certainly get a basic image editor with your camera. It's unlikely to be anything special, but it should enable you to crop, resize and sharpen your images - the three things you'll need to do before you display them on the web.

Digital photography is developing very rapidly, and the camera you choose today will be replaced by one that's twice as good for half the price by this time next year.