SLR, or single lens reflex, cameras remain the most popular type of interchangeable-lens camera, having been around since the 1940s.

The digital versions pick up from the tried and tested design of SLR film cameras, and digital SLRs remain hugely popular with enthusiast photographers and pros. As with the other camera types discussed here, there are different types of SLR for different market segments – from entry-level models aimed at people wanting to progress beyond point and shoot, to pro-spec warhorses.

Canon EOS 100D
The Canon EOS100D – the smallest and lightest SLR to date. Who needs a CSC anyway?

Entry-level models, notably the Canon EOS 100D, are compact too, so it's not always an obvious choice between an SLR and CSC. Here are some things to consider...

Sensor

SLR sensors are usually either APS-C (the same as some CSCs) or full-frame format.

As mentioned, a full frame sensor is the same size as 35mm film negative 'frame.' This means that its light sensitive pixels (photosites) can be larger than those on APS-C format sensors. So, more light can enter these larger photosites, which can mean better dynamic range and less noise compared to cameras with APS-C chips.

Also APS-C sensors, being smaller, only capture a portion of a scene compared to full-frame – the so-called 'crop factor'.

This is particularly good for wide-angle images, such as landscapes. However, this isn't to say that APS-C sensors are 'worse' than full frame, just different. Some photographers prefer the way the crop factor gives you more 'reach;' SLRs with APS-C sensors, and compatible lenses, are usually cheaper too!

Viewfinder

If you prefer a traditional optical viewfinder for composing images, rather than an Electronic Viewfinder or LCD, then it's SLRs all the way.

Nikon D7000
The Nikon D7000 – an excellent mid-range SLR, with 16.2Mp sensor and impressive high ISO performance

Bear in mind that cheaper SLRs have optical viewfinders that contain mirrors rather than the glass prisms and superior optics found in the viewfinders of higher-end SLRs.

Lens choice

Another big advantage of SLRs over the CSCs is the much wider choice of keenly priced lenses – you're plugging in to a whole photographic 'system.' Plus, some old Canon and Nikon lenses for film SLRs will also work on digital SLRs (though check for the particular SLR you are thinking about buying). There's also a much bigger used market for SLR lenses.

Which lens? Choose the best lens for your DSLR

Build and handling

SLRs tend be sturdy – even Nikon's entry level D3300 has a tough monocoque body – so they may be a better choice than a CSC if they're going to get some rough handling, but top-end CSCs also have a tough build and some, such as the Fuji X-T1 and Olympus OM-D E-M1, are weatherproof.

Just remember that higher-end SLRs tend to be much bigger and heavier than higher-end CSCs. Nikon's full-frame D800 weighs a hulking 900g (body only), compared to 407g for Sony's full-frame Alpha A7RCSC. Add a long lens and you're suddenly hauling around a lot of camera...

Extra features

All decent digital SLRs now shoot HD video, but as with CSCs, not all have built-in flash – the thinking being that higher-end SLRs will be used with more powerful stand-alone flashguns.

Canon EOS MKIII
The Canon EOS 5D Mark III – its full-frame frame sensor is outgunned by Nikon's 36Mp D800, but it's still a fantastic performer that won't slow your PC to a crawl

Built-in Wi-Fi and vari-angle screens are becoming more common on mid-range models, a good example being the Nikon D5300, but touch-control is thin on the ground.

How much should I spend?

Good entry-level SLRs, such as the Canon EOS 1100D, can be snapped up for under £250 / US$450 / AU$400 with a basic 'kit' lens, while a quality mid-range model, such as the Nikon D7100 costs around £840 / US$1,150 / AU$1,250 body only.

Full-frame SLRs such as Nikon's D610 start at around £1400 / US$1,900 / AU$2,000 body only, so you can see the price jump.

A quick word about rangefinders

Another type of camera we need to talk about is what's called a rangefinder. These use a dual-image rangefinding device to focus; when the two images correlate, you have perfect focus.

While they take some getting used to, rangefinders are still popular in the digital age, as they are usually discrete, compact and quiet. They also weigh less, since they don't have mirrors or prisms that flip.

Leica rules the roost when it comes to digital rangefinders, and you'll pay for a premium for this legendary name: even the entry level rangefinder, the Leica M, costs around £5,100 / US$7,000 / AU$9,000 body only.

If that seems excessive, note that rangefinder-style CSCs are now becoming popular, a good example being the Fujifilm X-Pro1.

Leica M
Leica M - The ideal rangefinder if you've got several thousand notes burning a hole in your pocket

Find your ideal camera

Now you know what type of camera you want, follow the links below to find out which model is best for you: