DSLRs remain the camera of choice for most semi-pro and pro photographers, even though some are now turning to high-end compact system cameras such as the Olympus OM-D E-M1 or Fujifilm X-T1. Although top-end SLRs are not cheap, they deliver a high level of performance, based around full-frame sensors; they also have a wide range of customisable controls, and support lots of specialist lenses, accessories and studio equipment.

As you'd expect from a camera costing the same as a decent used car, higher-end SLRs have myriad autofocus options, impressive ISO performance and often (but not always) fast continuous shooting. They tend to be built like tanks too, since they have to meet the demands of professional press, sports and adventure photographers, who are often working in demanding, deadline-driven environments. When it comes to choosing a top-end SLR, the biggest decision is whether to go for a full-blown pro model, such as the Nikon D4S, or to save money by opting for a camera that also appeals to advanced enthusiasts and semi pros.

The boundary between these two types of camera often blurs, however. Although you often see well-heeled enthusiasts toting the Nikon D800 or Canon EOS 5D Mark III, they are also widely used by fully paid-up professionals. Read on for more buying advice...

Canon EOS 5D mk III

Canon EOS 5D Mark III

  • Sensor size: Full frame
  • Pixel count: 22.3Mp
  • Screen type: 3.2-inch fixed LCD, 1,040,000 dots
  • Maximum continuous shooting rate: 6fps
  • Maximum video resolution: 1080p

This is a perfect example of a pro-spec SLR that also appeals to serious amateurs. While the 5D Mark III is a very powerful camera, it wears its power relatively lightly, and weighs nearly 400g less than the 1DX. At the heart of the 5D Mark III is a high resolution 22.3Mp sensor, and while this is outgunned by the 36.3Mp resolution of arch-rival the Nikon D800, it still delivers masses of detail – and the smaller raw files don't take up so much card space or computing power.

The 5D Mark III has a faster burst rate (6fps) than the D800, too, so this an impressive performance for a full-frame camera. While the 5D Mark III weighs less than the 1DX, it has the same autofocus system. The camera offers no less than 61 AF points, of which 41 are cross-type sensors and five are dual cross-type (its predecessor only had a nine-point AF system). Noise is very well controlled through the ISO range and a dual card slot adds to the camera's practicality. Unlike the D800, there is no pop-up flash, however. It's also a shame that the rear screen is fixed, but these are minor drawbacks on an otherwise excellent camera.

Read our full Canon 5D Mark III review

Nikon D800

Nikon D800

  • Sensor size: Full frame
  • Pixel count: 36.3Mp
  • Screen type: 3-2 inch fixed LCD, 921,000 dots
  • Maximum continuous shooting rate: 4fps
  • Maximum video resolution: 1080p

The Nikon D800's 36.3Mp sensor caused a big stir when it was released in 2012, offering the highest resolution of any Nikon SLR to date. While this enables superbly detailed images, you'll need to make sure your focussing skills (and lenses) can keep up, as any lack of sharpness is painfully obvious.

There were some worries about the greater risk of noise from such a high-resolution sensor, but it's very well controlled below ISO 3200. The D800 has a 51 point AF system compared to the 61 point system in the Canon 5D Mark III, but it copes admirably with tricky focussing situations. Indeed, both the AF and metering systems are identical to those in the Nikon D4, but at a much lower price. Considering its massive resolution and advanced features, the D800 is reasonably light at 1kg (2.2lbs) and the pop-up flash is a practical extra.

So what are the downsides? You may need to upgrade to a faster computer with more storage space to cope with the large raw files, along with lots of high-capacity memory cards. Another consequence of the high resolution is the laggardly 4fps continuous drive rate, so the D800 is much more suited to landscape and portrait photography than it is action and sports.