For the serious photographer, the digital SLR is the ultimate piece of kit. Digit guides you through the ever-expanding market.

Digital single-lens reflex (SLR) cameras are designed for serious photographers who want more control over how their photos look. They have several advantages over the more conventional point-&-shoot digital cameras. They let you swap out their lenses, and lenses and accessories from your existing 35mm film SLR camera are usually interchangeable if you use same manufacturer. For example, Canon's digital SLRs can use most of the several hundred available Canon EF mount lenses. Some older lenses and the Olympus E-1, which uses lenses specially designed for this camera, are exceptions.

The standout product in this round-up is the Canon EOS-300D, which at £765 is the cheapest of the models we reviewed. This 6.3-megapixel camera takes beautifully sharp pictures, with accurate, vivid colours, and it is very easy to use. Though not quite as robust or as feature-packed as some of its more professional cousins, it's a great choice for the serious photographer without a huge budget. Our other favourite is the Olympus E-1; although this model is more expensive, it is very easy to use and has a number of helpful features, such as an excellent noise reduction mode. The Canon EOS-1Ds is another outstanding camera. It produced the sharpest, best-looking images in our tests, though it costs over £4,500. You'll probably see cameras similar to this one, but costing much less, appear within the next couple of years.

Focal length

Although you may be able to use a standard film SLR lens on a digital SLR, there is a price to pay. The image sensors in digital SLRs are almost always smaller than a 35mm film negative, a difference that increases the effective focal length of the lens. This is great for zoom lenses because it increases the magnification; but when you are using a wide-angle lens, it decreases the angle of view.

The exceptions are the Canon EOS-1Ds and the Olympus E-1. The 1Ds has a sensor that's the same size as a 35mm negative, while the Olympus uses special lenses that provide the same angle of view as an equivalent film SLR lens.

In living colour

All the cameras tested produced images with impressively vivid colours. Overall, the three Canon models took top marks for colour accuracy. The Nikon D100 overemphasized the yellow, but we found this flaw easy to correct by using either the supplied Nikon View software or Adobe Photoshop, and once they were corrected, the images looked as good as those produced by the other cameras.

All of the models support an uncompressed RAW mode, which saves all of the information captured by the image sensor. But this mode also produces big files - often in excess of 10MB for a single image. It consequently makes viewing pictures in the camera's LCD screen a slow process, but the Canon cameras use an interesting trick - in RAW mode, they save a JPEG version of the photo as well that the camera can quickly display.

Noise annoys

Noise - speckling or mottling, most often visible in broad planes of colour such as sky - is an inevitable fact of digital photography. We saw noise in photos taken by all of the cameras, although most of the time these blemishes were barely noticeable. The Nikon D100 showed the most noise, but we wouldn't say it has a big problem. The images it produced still looked great when enlarged, with the noise being only just visible at lower ISO settings. The Olympus E-1 has a noise reduction mode in which the camera takes the photo and then takes another with the same settings but with the shutter closed. Finally it subtracts this noise-only image from the first, eliminating much of the noise.

Hands on

The downside of the creative control these cameras offer is that they can be much more difficult to use than a conventional point-&-shoot digital camera. The Canon EOS-10D's body, for instance, has a total of 17 buttons, two switches, and three dials, and it takes some time to learn which button does what. The Canon EOS-300D and the Pentax *istD are the easiest to use. Neither requires a huge amount of button pushing to access its settings. The Olympus E-1 puts controls you'd want to use while looking through the viewfinder (such as exposure lock and the focus point selector) under your right thumb for easy access, while the Nikon D100 offers two dials for shutter speed and aperture near the shutter button.

All of the cameras proved to be quick at focusing in good light, although in low light the EOS-300D often spent several seconds trying to focus. All of the models offer several user-selectable focus zones. The Canons provide an automatic depth-of-field mode, and this is very useful for getting both a nearby object and a distant one in focus.

The cameras we tested have a variety of metering modes, including spot, centre-weighted, and automatic. The Pentax and Nikon provide a dedicated dial, instead of buttons or a menu, for switching between metering modes.

Photos a la mode

The cameras all offer modes such as aperture-priority, shutter-priority, full manual, and program, but the Canon EOS-300D and 10D also include scene modes (such as sports and portrait) that set the camera up for the subject. For instance, the sports mode enables the camera to take photos in quick succession and keep quick-moving subjects in focus.

Most of the models connect to a PC over a USB 1.1 interface, and copying the large files takes a long time. The 1Ds provides a FireWire interface, while the Olympus E-1 includes both USB 2.0 and FireWire. Both of these faster connections make the process of transferring images much quicker.

While the EOS-300D is the standout camera of the group, there are several other attractive options. The Olympus E-1 is easy to use and takes great images, but it can't take existing Olympus lenses. The Pentax *istD is the smallest and lightest of the group, but the images were not as sharp as the others. The Nikon D100 is a very flexible camera, but the others have more accurate colours and less noise.