Practical Artistry: Light & Exposure for Digital Photographers

38 Understanding Exposure

Measuring Light

Measuring Light

The art and craft of measuring light is used to establish

a base reading for setting your exposure. This “reading”

is a sample exposure given the amount of light available

for you to capture.

Once you have a sample light reading, you can use the

components in the exposure equation to choose your

exposure settings to set shutter speed, aperture, and

sensitivity.

The most commonly used tool for measuring light is

your camera’s light meter. If you choose an ISO and

set the camera on auto exposure, you can get an initial

light reading, with a supplied shutter speed and f-stop.

You can get initial light readings in shutter-preferred

mode by pre-selecting the shutter speed. The camera

will supply the f-stop.

Using aperture-preferred mode allows you to obtain a

light reading by pre-selecting the aperture. The camera

gives the shutter speed.

Aperture or shutter preferred modes are often more

convenient than fully automatic for getting exposure

readings because you may have some idea already of

where you need one of the exposure components to

be set.

Depending on your camera model, you can get a light

reading simply by turning the camera on and pointing

it at your subject, or you may have to partially depress

the shutter release button. Check your camera manual

for specifics.

A big issue is what you point ...