DSLRs for beginners
Digital SLRs have a reputation for being complex and intimidating, but they can actually be as straightforward to use as a regular compact digital camera. The important thing is to choose a camera that you feel you can get to grips with.
A typical entry-level SLR has plenty of automatic control options, such as 'scene modes' for landscapes, portraits and other subjects, which allow the user to concentrate on timing and composition while the camera handles exposure and white balance etc. The more advanced exposure modes (aperture priority, shutter priority and manual) are also usually present to give 'room to grow' as you gain in experience.
Most entry-level SLRs are small, light and inexpensive. They lack the robustness and features of more expensive models, but they're still capable of taking top-quality shots. If you choose last year's model rather than the very latest, you can pick up a real bargain that still delivers all the features and image quality you need.
DSLRs for enthusiasts
Digital SLRs designed for enthusiasts generally have more of everything – more megapixels, faster continuous shooting, more advanced features, better movie modes and other options designed for photographers who've moved beyond the basics.
These cameras will still have fully automatic modes for new users, or for situations where you don't have time to mess with manual adjustments, but when you do want to take control you'll find it easier than it is with a beginner model.
Digital SLRs for enthusiasts are generally larger, heavier and more robust. They may have metal construction and weather sealing for adverse conditions and some full-frame DSLRs now fall within the price range of keen photographers.
DSLRs for professionals
Professional DSLRs don't always have the highest resolution sensors. Pros look for different things in their cameras, and one of the primary factors is robustness and longevity. Pro DSLRs have strongly-made metal alloy bodies, no-fuss controls which make no concessions for novices but are built to withstand hard use in all kinds of conditions, and have larger-than-usual batteries so that they can shoot for longer.
Some pro models bring state-of-the-art autofocus systems and high continuous shooting speeds that you won't get in amateur cameras. These are designed for busy sports, wildlife or press photographers.
Some pro DSLRs are designed for speed (Nikon D4s, Canon EOS 1D x) while others are designed for resolution (Nikon D810, Canon EOS 5DS).
DSLR features to look for
Brand/lens mount: Canon, Nikon and Pentax all make digital SLRs, but each one uses a different lens mount. You can't put Canon lenses on a Nikon, or Nikon lenses on a Pentax. Each of these makers offers a good range of interchangeable lenses, though Canon and Nikon offer the widest choice and availability.
Sensor size: Most DSLRs have APS-C sensors measuring around 24mm x 16mm. But some DSLRs have full-frame sensors. These are the same size as 35mm film, and twice as large as APS-C. This is what the professionals choose, but the cameras are much more expensive and the lenses are bigger and bulkier.
Megapixels: Surprisingly, perhaps, there's not much to choose in terms of megapixels between cameras for beginners and those for pros. Most entry-level DSLRs now have 24MP, and only the top pro DSLRs offer more.
Movies: Just about all DSLRs now shoot full HD movies, but although the specs may look the same the real differences are in the details. Top cameras will be able to shoot at higher frames rates like 60fps or 50fps for smooth slow motion. They can save uncompressed footage 'live' to external recorders for better quality and will have both microphone and headphone sockets for better audio recording.
Articulating display: DSLRs can also be used in 'live view' mode, where you compose the image on the screen on the back of the camera. A tilting or fully articulating display can be helpful here for composing shots at awkward angles.
Continuous shooting: A basic camera might be able to shoot continuously at 3-4 frames per second, but more advanced models can shoot at 6-8fps, while pro cameras can hit 10-12 frames per second. This might not matter much for everyday photography, but it's important for sports and action.
Construction: Beginner-orientated DSLRs are lighter and more plasticky than the pro models, but they're perfectly well made and should last for years in the hands of any reasonably careful owner. Pro cameras have metal bodies, weather sealing around the joints and buttons and shutter mechanisms with a longer life expectancy.