Best SLR: which should you buy?

We explain how SLRs work, what to look for and how to choose the right one

Starus panel on DSLR
More advanced SLRs have illuminated status LCDs on the top to display key shooting information.

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. The Nikon D810 is unique in this category, too, for having a 36-megapixel sensor – 50% higher than any competing DSLR – its predecessor, the D800/E, was a favourite amongst landscape, portrait and commercial photographers.

DSLR shutter
Professional digital SLRs have shutter mechanisms with a higher life-expectancy. The shutter in the D810 is rated at 200,000 cycles (shots).

See our list of top DSLRs for professionals.

DSLR features to look for

Touchscreen
Many beginner and enthusiast SLRs have vari-angle displays, and some have touchscreen control, like regular compact digital cameras.

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 sensors measuring around 24mm x 16mm – about the same size as old APS film.This is many times larger than the sensors in compact digital cameras, and it's why DSLRs and other cameras with big sensors offer such a quality advantage. But some DSLRs have full-frame sensors. These are the same size as 35mm film, and twice as large again. This is what the professionals choose, but the cameras are much more expensive and the lenses are bigger and bulkier.

Wi Fi
Wi-Fi control is becoming increasingly popular. Some SLRs have it built in, while some use a small plug-in adaptor bought separately.

Megapixels: Surprisingly, perhaps, there's not much to choose in terms of megapixels between cameras for beginners and those for pros.

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. A better camera will also offer more manual control over the camera settings while filming.

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, not in the viewfinder. A tilting or fully articulating display can be helpful here for composing shots at awkward angles, and it's an advantage for shooting movies too.

Continuous shooting: A basic camera might be able to shoot continuously at three to four frames per second, but more advanced models can shoot at six to eight frames per second, 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 are heavier, with metal bodies and weather sealing around the joints and buttons. The shutter mechanisms will have a much longer life expectancy too – 200,000 shots and more, in some instances.