Okay, welcome back. In the first of this series we covered the basic underpinnings of exposure; if you haven’t read that one, I suggest checking it out first.

Today we’re going to start on aperture in photography. We’re going to break the topic of aperture into nice and small chunks, because there’s a lot to go over and each segment demands its own explanation.

Aperture, Part 1: What The F (number)

Probably the trickiest thing to get your head around, so let’s start from the start: what is aperture anyway?

An aperture is an opening, and in photography it is a particular opening inside your lens that allow light to reach your camera sensor. We can change the size of this opening to allow more or less light in.

We use f-numbers to describe the size of a lens aperture. Think of it as a scale, from very wide all the way up to very narrow. Here’s the usual range:

wide — f/1.4 f/2 f/2.8 f/4 f/5.6 f/8 f/11 f/16 f/22 — narrow

And minus the ‘f’, that would be:

wide — 1.4 2 2.8 4 5.6 8 11 16 22 — narrow

Let’s break up all the figures with a picture:

F-numbers don’t represent a physical measurement - they represent the ratio between the focal length of your lens (35mm, 24-70, etc etc) and the changeable diameter of the lens aperture. For example, a 50mm lens set to f/2 will have an aperture diameter of 25mm. At f/4, the aperture diameter would be 12.5mm. This is why a smaller f-number equals a wider aperture, which can be confusing at first.

A final note to help you memorise the scale: it doubles with every second number. For example, f/2 doubles to f/4 which doubles to f/8.

See you soon for part three!