We explain the finer points of aperture. What is aperture? How does aperture affect exposure? How does aperture change depth-of-field? What is aperture priority? What are f-numbers? What aperture setting produces the sharpest pictures?
The combination of aperture, shutter speed and ISO determines the exposure of the image -- in other words, how dark or light it is.
Aperture refers to the opening inside a lens which can be made larger and smaller to control how much light reaches the sensor when the shutter opens.
Aperture also has an important secondary role. Along with focal length, it influences depth-of-field, or how much of a scene is in focus either side of the point you actually focused on. A narrower aperture setting increases depth-of-field, while a wider aperture setting reduces it.
With a wide aperture it’s possible to put a person’s face in sharp focus, while everything in the background and foreground falls away into a soft blur. This is really useful for isolating an element so it appears to “pop” out of the photo...