Camera College

There’s more to using lenses than choosing a focal length that suits the size of the subject. Where you stand makes a huge difference to the look and feel of your pictures too

It’s all a matter of perspective...

Last issue we looked at lenses and how the choice of focal length and the size of the imaging sensor inside the camera determine the angle of view – in other words, how much of a scene or subject can be captured in a single shot.

The angle of view isn’t a measure of the physical distance recorded across a scene, but rather it’s the angular distance, which is expressed in degrees. A wideangle lens, as the name makes plain, has a wide angle of view, while a lens with a longer focal length gives a narrower view. If you’re using a zoom lens, you can simply zoom the lens in and out to change the angle of view.

You can also increase or decrease the amount of a scene that is recorded in a picture by physically moving the camera further from or closer to the subject. This can have a dramatic impact on the look of your pictures – much more so than standing in the same place and zooming a lens.

If you take two photos of the same subject – one using a short focal length and one using a long focal length, but moving the camera each time so that the subject remains the same size in the frame – the resulting pictures will look strikingly different; this is a result of the change in perspective.

When we talk about perspective in photography, we’re referring to the spatial relationship between objects. Changing the focal length doesn’t change the perspective – moving

from a short focal length to a long one means that objects will simply fill more of the picture – but changing the position of the camera does.

If you want an object to fill the frame when you’re shooting with a short focal length, you need to be physically close it. This creates ‘extension distortion’, where features close to the camera appear much larger than those in the distance. While it can help to exaggerate the sense of depth in a picture and draw attention to a subject that’s close to the camera, this effect doesn’t give the most flattering results when you’re photographing portraits – unless you’re a fan of the caricature look, with noses looking disproportionately bigger than the rest of the face.

If you want to photograph a subject so that it appears the same size using a longer focal length, you need to shoot from farther away. The narrow view offered by a long lens means that it’s easier to isolate individual subjects from their surroundings. A much smaller area of the background is included in the shot, and as a result it appears magnified and much closer to the subject than it is in reality. This

A smaller area of the background is included in the shot, and as a result it appears magnified and much closer to the subject than it is in reality

is what’s known as ‘compression distortion’. It’s an effective way to make elements of your composition appear densely packed together. You can use this attribute to give your portraits a more professional look, sandwiching a sharply rendered person between a blurred foreground and a blurred background to make them really stand out.

There are some subjects where telephoto lenses just go with the territory – including sports and wildlife, where you may not be able to get physically close enough to use a shorter focal length. But reaching for a long lens also gives you more creative options when you’re shooting anything from landscapes to fine art.

Of course, the extreme perspectives afforded by using both very short and very long focal lengths can draw attention to themselves in a picture, which can end up being all about the ‘look’ rather than the subject itself. While this may not be a bad thing in itself, what if you want a more natural look?

Full-frame focal lengths in the 40-50mm range (and their cropped-sensor equivalents) are said to give an equivalent view to the human eye. You don’t have to be too close or too far from the subject to get a suitable image size, so the perspective distortion is minimal. These ‘standard’ lenses essentially become ‘invisible’, allowing viewers to concentrate on the subject of the picture without being distracted by the optical effects associated with extreme focal lengths.

Of course, the extreme perspectives afforded by very short and very long focal lengths can draw attention to themselves in a picture