All About Aperture
Practical Photography Magazine
Last month we learned about shutter speed and how to make water blur with a
longer shutter speed. Have you gone out and tried that yet? It's springtime and
the crocus and daffodils are out - time to get out and try these methods and
improve your skills.
Aperture governs your depth-of-field, and it determines where the viewer's eye is
drawn to in a picture. Impact in our images - impress those judges. This is why
we need to learn about aperture.
What does the aperture do?
The aperture refers to how much light the lens lets through. Inside the lens
there's a circle of blades called the iris (similar to the eye) that opens and closes
to let more or less light through. The different sizes are given numbers
(f/numbers) to tell you how much light it is letting through.
As well as controlling the amount of light, the aperture also influences the amount
of the images that's in focus, known as the depth-of-field. A wide aperture (f/2.8
to F/4) gives the smallest area that's in focus, while a small aperture (f/11 to f/22)
ensures the greatest area is in focus.
Although the aperture has a major effect on the depth-of-field, it's not the only
factor. Longer focal length lenses have less depth-of-field than shorter ones, so if
you want the greatest amount of your image in focus use a wide-angle lens.
Depth-of-field also decreases the closer you are to the subject. The advantage of
the digital camera is that you can experiment without wasting film, so if you have
a digital camera, find yourself some subjects and just practice.
How do I control the settings?
You'll find an aperture-priority mode on your camera, most commonly accessed
via the Av or A setting on the mode dial. This mode allows you to set the aperture
and the camera will automatically set the appropriate shutter speed.
You can change the aperture setting by turning the control dial on the camera,
with the value displayed on the LCD screen and al