2) All About F-Stops
The Aperture opening can be adjusted to control the amount of light which is allowed to reach the film or digital sensor of the camera. In low light situations, you can set aperture wider to let more light in, or close it up very small to reduce the amount of light reaching the sensor in bright light situations.
Apertures have a size scale called f-stops. You may have seen a number like f-4.5 or f-8 display on the info screen when you’re taking a photograph, and wondered what it meant.
The f-stop scale looks like this.
These are the most common f-stops for cameras of all types. (Some cameras have 1/2 or 1/3 stop settings in between these, but don’t worry about that when you’re still trying to grasp the concept.)