Digital cameras have evolved from toys into serious devices, capable of giving many film-based models a run for their money, while boasting many unique features: the ability to capture short movie clips, instantly review shots using built-in screens and make slide shows on TVs. Their memory cards can be used again and again, and there’s no more scanning when it comes to emailing pictures or using them in DTP newsletters.

A good digital camera can be the ultimate imaging device, but there’s plenty to watch out for. Supplied memory cards may only squeeze on a handful of pictures, the battery might be dead in just a few hours and you could spend a fortune on getting prints made. Then there’s the impenetrable jargon. So if you’re thinking of investigating in a digital camera, here’s what to look out for.

Megapixels

Digital cameras use millions of dots to make up their pictures. Their total number is known as the resolution and is measured in megapixels. The more pixels you have, the more detail captured, and the bigger the print you can make before you start seeing the dots as blocky squares. In tests with colour inkjets, the maximum size you can print with decent quality are as follows: 5 x 4 inches - 1 megapixel; 8 x 6 inches - 2 megapixels; 10 x 8 inches - 3 megapixels; 11 x 9 inches - 4 megapixels; and 12 x10 inches - 5 megapixels.

Note that Fujifilm’s SuperCCD cameras may deliver images with 4.3 or 6 megapixels, but they use a lower resolution sensor with clever scaling. In tests they resolve no more detail than 2.4 and 3.3 megapixel cameras respectively.

Zooms

Forget about digital zooms, which merely crop the image and enlarge the central portion, thereby losing quality. The important figure is the optical zoom, which normally operates in a 3x range, roughly equivalent to a 34mm-102mm lens on a 35mm camera.

Memory

Using the best-quality compression settings, an average 2 or 3-megapixel camera will create image files measuring between 0.5 and 1.5Mb each. However, most cameras are only supplied with 8Mb or 16Mb cards, which means an average of around 10 pictures can be stored. Consequently, you should budget for a bigger memory card straightaway. It will cost between pound;30 and pound;50 for a 64Mb card depending on format. Compact Flash the is cheapest, while Sony’s Memory Stick is the most expensive.

Sony’s Mavica cameras (see p54) uniquely record their images on to either floppy discs or rewritable 8cm CDs. Floppies may only have 1.4Mb capacity, but 8cm CDs can store up to 156Mb, which means there’s room for plenty of pictures. The Mavicas may be quite large to accommodate the floppy or CD-RW drives, but at least the media can be inserted into almost any PC.

Battery

Digital cameras employ either lithium-ion or AA batteries. Both are rechargeable, but you will only get between one and three hours of solid use out of a set, which translates into around one to three days of shooting. So if you’re more than a couple of days from the mains, make sure you’re carrying spares.

AAs cost a few pounds compared to around pound;50 for a lithium pack, and are more widely available. On the other hand, lithium packs are smaller and lighter than a set of AAs and take about 90 minutes to recharge, compared to overnight.

Recommendations

The following models come highly recommended and will work with any Mac or PC equipped with a USB port. All prices include VAT, but not educational discount.

The cheapest 2-megapixel models start at around pound;250 with Kodak’s DC3800, but it doesn’t have an optical zoom. For pound;300, you’ll get Kodak’s DC3600 or Sony’s P50, with 2x and 3x optical zooms respectively.

The cheapest 3-megapixel models come in just under pound;500 and you can’t go wrong with Nikon’s CoolPix 885 or Epson’s PhotoPC 3100Z. Step up to 4 megapixels and for just under pound;700 you will find models like Sony’s S85, Canon’s G2 and Olympus’ C-4040ZOOM. Each of these 3 and 4-megapixel models has a 3x optical zoom, full manual exposure control and great handling.

If you can stretch to pound;900, then go for a 5-megapixel model. Sony’s F707 boasts a 5x optical zoom and night modes, while Nikon’s CoolPix 5000 has a flip-out screen and a wider-angle lens than most digitals.

As with all cameras, though, the most important thing is to try them out for yourself, as one that feels great to one person could feel unwieldy to another.

Gordon Laing is a freelance writer and broadcaster and former editor of Personal Computer World magazine. Hear him every Thursday night, 7pm-9pm, on The Lab, LBC 1152AMwww.lbc.co.uk Digital dos and don’ts

Do get at least 2-megapixel resolution or, more usefully, 3 megapixels.

Don’t bother with 1 megapixel cameras unless the images are for screen or online use only.

Don’t bother with 4 or 5-megapixel versions unless you want to print bigger than A4.

Do buy a new memory card immediately. The one supplied is virtually useless.

Don’t pay attention to digital zooms - they crop, then enlarge images, reducing quality.

Do get a macro mode of 5cm or less if you’re into close-up shots of tiny subjects.

Do get an optical zoom of 5x or 10x if you shoot distant subjects like wildlife.

Do carry spare batteries if you don’t get the chance to recharge every couple of days.

Don’t throw out your camcorder yet. Movie clips on still cameras are short and poor quality.

Do try out the kiosks at Jessops - 40 prints for pound;7 is much cheaper and quicker than an inkjet printer.