Aperture Mode is where you can change the size of the lens to let less or more light in. The aperture is the opening in the lens.
For example, when you press the shutter release button (the button used to take the picture) a hole opens up that allows your camera’s image sensor to get a glimpse of what it is you want to take a picture of.
The aperture that you set on the camera (which is measured in f-stops) is what affects the size of that hole.
The larger the hole the more light that gets in – the smaller the hole the less light.
As can be seen in the diagram above, the lower the f-stop number is, the more light that enters the lens and the bigger the aperture. The higher the f-stop number the less light that enters into the lens and the smaller the aperture.
WHAT DOES THE APERTURE CONTROL/AFFECT WHEN CHANGED?
DEPTH OF FIELD
Depth Of Field (DOF) is how sharp or blurry the area behind your main focus is.
The aperture affects the DOF, as a low f-stop number (high aperture) will make the background blurry and the foreground sharp and clear, while high f-stop number (low aperture) will make both the foreground and background clear.
Low f-stop number = Blurry background
High f-stop number = Clear background
This is a photo of a fence. In this image, the DOF is low, as both the foreground and background are clear. The f-stop number is high.
This is the same fence. In this image, the DOF is high, as the foreground is clear while the background is blurry. The f-stop is low.