Triangle of exposure

Three elements constitute the triangle of exposure: aperture, shutter speed and ISO:

  • Aperture (f/N): light passing through the lens

  • Shutter speed: how long the shutter stays open

  • ISO: image sensor’s sensitivity to light

A small aperture (i.e. f/16) gives a deep depth of field and is usually used for landscape.

A fast shutter speed (i.e. 1/1000 sec) is used to freeze motion, like birds in flight or action shots. It also gives a shallow depth of field.

A slow shutter speed (i.e. 1/4 sec) is great for motion blur like milky water effect or rain streaks. Slow shutter speed is also used for night photography or poorly lit areas. In any case, a tripod is highly recommended for long exposures.

Before you adjust the aperture, shutter speed and ISO on your camera, you need to ask yourself: What effect do I wish to create? What is the mood of my image? What am I trying to tell?

Use the light meter in your camera to help you get the proper exposure. Light is measured in Exposure Value (EV) and typically displays in cameras from - 3 EV to + 3 EV

-3 _____ -2 _____ -1 _____ ∆ _____ 1 _____ 2 _____ 3

under exposed correct expo. over exposed

Once you’ve taken your shot, check the histogram and readjust your exposure if necessary.

Time to practice. Let me know how it goes!