As it goes without saying but it always gets better by saying it, a quick reminder. Aperture is one of the 3 parameters that influence the exposure of a photo as discussed by It corresponds to the opening diameter of the diaphragm when triggered.

How Do We Know Which Opening We Are Going To Use?

The opening is measured in “number f “. On your device, this is written as “f / number”. For example, f / 3.5 or f / 22. Where many beginner photographers get lost is that f / 3.5 represents a larger aperture than f / 22 for example! It would be useless to go into the technical details, but note that:

  • The higher the number f is large, the more the opening is small
  • The higher the number f is small, the more the opening is large

It’s just like a fraction: 1/4 is smaller than 1/2. But since this is an f, it’s not as intuitive for everyone, but good, that’s how it is!

If you look closely at your lens, you will find an inscription of the type 18-55mm 1: 3.5-5.6 The “1: 3.5-5.6” in fact represents the maximum aperture of your lens at its extremes of focal length (or zoom if you prefer).

How To Adjust The Opening?

You can modify it in two different modes: manual mode (M) or aperture priority mode (Av or A). (for more details, see the article on camera modes)

Manual Mode (M)

In manual mode, if you want to change the aperture you need to keep the button “Av” or “+/-” on your device down and turn the dial. (On some higher-end cameras, there are 2 dials, one of which controls the aperture, and the other controls the shutter speed).

Remember that changing the aperture will change the exposure (, so you may need to play on one of the other two pillars to maintain normal exposure. That said, I do not recommend that you try manual mode until you are aware of the 3 elements of the exhibition.

Aperture Priority Mode (Av Or A)

The opening priority mode is aptly named: when you use it, your priority is to set the opening. You will therefore only set the aperture (with the dial), and the camera will do the rest, namely set the shutter speed, and the ISO if you left on auto ISO.