SLR cameras buying guide

Every phone, MP3 player and tablet computer has a camera in it these days, so why would you want to buy an expensive, heavy digital SLR?

Because you want your photos to stand out from the tens of thousands that are uploaded to photo sharing sites every day? Perhaps.

Because a digital SLR gives you more creative control over your pictures? Definitely.

If you're a budding amateur who's just thinking about getting serious about their photography, or an old hand who's looking to finally switch to digital, here's everything you need to know about digital SLRs.

What's an SLR?

The acronym stands for 'Single Lens Reflex'. Strictly speaking it only refers to cameras with an optical viewfinder - an old-fashioned eyepiece rather than a screen - which can see the image to be taken through the lens of the camera.

Light is reflected up away from the digital sensor by an internal mirror. When a photo is taken, the mirror moves out of the way for a split second, allowing the image to be captured.

However, the term is now often used for any camera which has interchangeable lenses - a hallmark feature of traditional SLRs. This is when you can remove one lens and replace it with another to get a wider angle or longer zoom. There's a new generation of 'mirrorless SLRs' which use an electronic viewfinder but have interchangeable lenses.

SLRs versus compact cameras

  • SLR lenses tend to be much higher quality.

  • You may think that a compact camera with a 5x zoom is better than an SLR lens that doesn't zoom at all, for example, but there are lots of physical compromises that have to be made to make a small lens work so hard.

  • Also, SLRs tend to focus faster than compacts, making them better for action photography.

  • SLRs have larger sensors than compact cameras. That's larger in terms of physical size, not megapixels.

  • A compact camera has a sensor about the size of a child's little fingernail, while SLRs use film-sized sensors to capture more detail and take better pictures with less light.

  • There are lots of very lightweight mirrorless SLRs from the likes of Sony, Panasonic and Olympus, but they're still bigger and heavier than the majority of compacts.

  • A good SLR will last for years, though, and you can build up a good collection of lenses, flashguns and so on over a long period of time. Many lenses that were first designed 20-30 years ago still work on modern DSLRs.

SLR video

Almost all new SLRs can record video in 1080p quality that's so good, it's broadcast quality.

Many professional filmakers use digital SLRs to record everything from documentaries to adverts to entire episodes of the US comedy, House.

Nikon, being very clever, recorded the latest TV advert for its budget D5100 SLR using - you guessed it - a D5100.


  • Compact camera: one of the distinguishing features of an SLR camera is the ability to remove the lens and swap it for another. Compact cameras, on the other hand, have a lens that is fixed in position to the camera body.

  • Full frame: most SLRs have a sensor which is the same size as old fashioned APS film, found in compacts from the 1990s. The more expensive ones have a 'full frame' sensor, which is the same size as 35mm film. Because these are physically larger, they are able to capture even more detail in even lower lighting conditions.

  • Micro Four-thirds: a sensor and lens standard introduced by Panasonic and Olympus which uses smaller sensors and mirrorless bodies to create lightweight cameras with most of the professional qualities of an SLR, including interchangeable lenses and better picture quality. The name is taken from the aspect ratio of the sensor, which is the traditional TV standard of 4:3, while other SLRs usually use a 3:2 ratio sensor.

  • Focal length: is the distance from the base of the lens to the sensor in millimetres.

  • Aperture: a series of blades which can be opened and closed to let more or less light on to the sensor, depending on how well lit the image to be captured is.

  • F-number: a number preceded by an 'F', which is defined by the ratio of the focal length to physical size of the aperture. The lower the F-number, the 'faster' the lens, and the more light it lets in. So a lens with an F number of F1.8 can take photos without a flash indoors, but shooting at the same settings will overexpose outside.