Track 1 · Exposure5 min read
LESSON 01
Aperture
The opening inside the lens. It decides how much light gets in and how much of the picture is sharp.
ONE FULL STOP HALVES THE LIGHT
- f/1.4
- f/2
- f/2.8
- f/4
- f/5.6
- f/8
- f/11
- f/16
← MORE LIGHT · LESS IN FOCUSLESS LIGHT · MORE IN FOCUS →
What the number means
An f-number is the focal length divided by the width of the opening. So f/2 on a 50 mm lens is an opening 25 mm across, and f/8 on the same lens is about 6 mm. A small number means a big hole.
Light
Each step in the row above lets in half the light of the one before it. Going from f/2.8 to f/4 is one stop darker; to keep the same brightness you double the shutter time or the ISO.
Focus
A wide opening gives a thin slice of sharpness: the eye is sharp and the ear is soft. Close it down and more of the scene, front to back, comes into focus.
Try it today
- 01Set the dial to A or Av, aperture priority.
- 02Put a face or a cup a metre away.
- 03Shoot it at the smallest f-number your lens has.
- 04Shoot it again at f/11 without moving.
- 05Compare the background in the two frames.
PRACTICE
All how-tos →From the feed
How-to pieces where the aperture does the work.
