What is Aperture?
Put simply – Aperture is ‘the size of the opening in the lens when a picture is taken.’
When you depress the shutter release button of your camera a hole opens up that allows your cameras image sensor to catch a glimpse of the scene that you want to capture. The aperture that you set determines the size of that hole. The larger the hole the more light that gets in – the smaller the hole the less light.
Aperture is measured in ‘f-stops’. You’ll often see them referred to as an f/number – for example f/2.8, f/4, f/5.6,f/8,f/22 etc. Moving from one f-stop to the next doubles or halves the size of the amount of opening in your lens (and the amount of light getting through). Keep in mind that a change in shutter speed from one stop to the next doubles or halves the amount of light that gets in also – this means if you increase one and decrease the other you let the same amount of light in – very handy to keep in mind).
One thing that causes a lot of new photographer’s confusion is that large apertures (where lots of light gets through) are given smaller f/stop numbers and smaller apertures (where less light gets through) have larger f-stop numbers. So f/2.8 is in fact a much larger aperture than f/22. It seems the wrong way around when you first hear it but you’ll get the hang of it.
Depth Of Field & Aperture
Depth of field (DOF) is the amount of your shot that will be in focus.
A large depth of field means the majority of your photo will be in focus whether it’s really close to your camera or further away.
A small or shallow depth of field means that only part of your photo will be in focus, and the remainder will look fuzzy (out of focus).
The aperture you select will have a big impact on the depth of field. A large aperture (remember it has a smaller “f” number) will decrease the depth of field, while a small aperture size (larger “f” number) gives you a larger depth of field.
It might seem a bit daunting and confusing at first just remember a small “f” number means a small/shallow DOF & larger “f” numbers a larger DOF.
So get your camera out and experiment with the different aperture sizes and see how it all relates.