Choose the right camera : Things to consider when taking landscape photos

What to look for

Above else else, when buying a camera for landscapes, look for a wide angle lens and a dedicated aperture priority mode. Everything else, including automatic panorama stitching, is nice to have but far from essential.

Wide angle lens

The angle of view of the lens is specified in millimetres. The smaller the number, the wider the angle of view, so a fully retracted 18-55mm kit lens on a dSLR will usually capture a broader swathe of each scene than a 28-200mm lens on a compact. We say 'usually', because in practice you need to do a little bit of maths to work out how they compare.

All focal lengths are calculated with reference to a single frame of 35mm film. Comparatively few cameras have a sensor this size, though, so you need to multiply the stated focal length of the lens by the number of times that the sensor in your camera would fit into a 35mm frame. That number is known as the crop factor.

Most entry-level dSLRs use a sensor roughly the size of Advanced Photo System Classic (APS-C) film. This is roughly 1.5x smaller than a 35mm frame, so to work out how the lens really performs you need to multiply its focal length by around 150 per cent. That makes our 18mm lens behave like a 27mm unit, at which point its angle of view is barely any wider than the 28mm angle on our example compact.

When selling compacts, most manufacturers have already done the maths for you and used the result on the box or the specifications. So, unless their focal lengths kick off in the region of 4-5mm you needn't convert them yourself.

Aperture and depth of field

Behind the lens you'll find a series of blades that open and close to let in more or less light. Although these can be used to adjust the exposure they are more effectively employed to control the depth of field in your image.

Depth of field describes the distance between the closest and furthest objects that remain in focus in your frame. So, a shallow depth of field would be great for portraits where you'd want your subject's face sharp, and their surroundings gently blurred. When shooting landscapes you want the opposite: as much of the frame as possible in focus, which you'll achieve by narrowing the aperture.

Look for a mode marked A, Av or Aperture Priority, and use your camera's controls to dial in the highest possible value this mode will allow. This value -- the f-stop -- controls the extent to which the blades intrude into the opening through which the light must pass on its path from the lens to the sensor. The higher the value, the more the blades intrude; the more they intrude, the smaller the aperture; the smaller the aperture, the more of your scene you'll keep in focus.

Look for a camera that offers a minimum aperture of at least f/8. The closer you can get to f/22, the better. You may need to dig a little further than usual into the camera specs to obtain this information, as manufacturers' headline specs usually only specify the widest apertures you can achieve when the lens is in its wide angle and telephoto positions, such as f/3.5-f/5.9.

Landscape photography wish list

• Narrow minimum aperture
• Dedicated aperture priority mode
• Wide-angle lens