To put this concept into practice, let’s discuss the connection between f-stop and aperture. When photographers refer to an f-stop or f-stop number, they are speaking directly about aperture. You might also hear phrases such as “opening up,” “stopping down” or “shooting wide open.” Put simply, these phrases all relate to the aperture’s ability to open wider or close smaller when letting in available light.
A large aperture (remember, large pupil size) is measured using a low f-stop number, such as f/1.4. When the maximum aperture (lowest f-stop number) is used, this is referred to as “shooting wide open” — essentially, letting in the most light possible. On the opposite end of the spectrum, a small aperture (remember, small pupil size) is measured using a high f-stop number, such as f/22. Since a small aperture takes in less light, you’ll be “stopping down” each time a higher f-stop number is used.
To help visualize the connection between f-stop and aperture, take a look at our diagram below: