Making light work of photography

A play of shutter speed, aperture size and film speed can help you with motion shots or dim lighting. JEFFREY TSANG shows you how

DIGITAL cameras provide so many functions that photography has become a point-and-click affair.

But for those of you who wonder why you still cannot get great photographs, all you need is some understanding of photography and how to use your camera's functions to your advantage.

The first is the balance of light. Besides focus, a photograph depends on the shutter speed and aperture size. Playing with these two can have different effects on an image.

For example, if there is rapid movement - shooting a sprinter or shooting from a moving car - it's best to choose a faster shutter speed to freeze the action, usually from 1/250s to 1/1000s.

For fully automatic cameras, select the Sport mode on the dial, often denoted by an icon of a running man.

What if the light is low, say at dawn or in a dimly lit room, and the action is still fast? There is the flash, of course, but the sportsman might be blinded by it.

You can shoot with a fast shutter in low light by adjusting the third component of the exposure formula - film speed, or 'sensitivity' in most digital cameras.

Besides the Auto setting, which may be good enough for general use, most digital cameras allow manual selection of sensitivity. These are the ISO numbers (or DIN/ASA standard of film) - the high numbers like ISO 400 and above indicate that it is a 'fast film'.

If the ISO is fast you can probably use a relatively fast shutter speed for your action photography. The only problem with using fast film is the resolution, or noise - less photographic detail is effectively captured.

When you want to give the impression of movement, however, such shots can be achieved by setting a slower shutter.

So you can play about with shutter, aperture and sensitivity to capture action, and use a manually set shutter speed, or Shutter-Priority mode, to do so.

F is for depth

What about setting or fixing the aperture? When might that be useful

An aperture is the hole through which light enters the camera, and its size can be adjusted. Aperture is spoken of in 'f-stops' - the larger the number, the smaller the aperture. Good lenses are often measured by how small the 'f' number gets, with most around f2.8.

One thing that the aperture controls is depth - how wide the range in which the subject will be in focus.

When the depth is great, then a subject standing 10m away is still in sharp focus even though the lens is focused at 5m. When there is no depth, the subject might be out of focus if just 1m out of range.

It is the same with your eyesight: Objects seem sharper in bright light. This is because the pupils constrict and depth is improved, so everything is in focus even when eyesight is poor.

In portraits, it is best to reduce the depth such that the background is blurred, which contrasts against the subject in sharp focus.

To achieve this, set your camera to Portrait or Aperture-Priority mode. Or go to a manual setting and set the aperture wide - say f5.6, or larger.

With a play of aperture for depth, shutter speed for action and sensitivity for resolution, you are set to get creative!

Jeffrey Tsang runs his own PR consultancy.


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