What’s the big deal about aperture? Should you know anything about it when comparing cameras (or lenses)? Does the terms f/stop, f/value, aperture value confuse you?
Consider that for light to expose the image sensor, it must be let inside the camera. The aperture is that hole that is opened to allow light to enter your camera. It can also work in combination as a shutter so that it opens to let light in and closes to stop light from getting in. The amount of time it stays open is called the shutter speed. For cameras that have a separate shutter, the aperture will stay opened at the value you dial in (or the camera automatically dials in) while the shutter will open and close to limit the time light exposes the image sensor.
The aperture is the size of the lens opening. You adjust its size depending on the light intensity. The less light there is, the wider you may have to open the aperture. A large aperture is denoted by a small number, e.g. F1.8 or f/1.8, while a small aperture is denoted by a large number, e.g. F16 or f/16. A “fast” lens is one with a large maximum aperture.
Learn all about aperture in our tutorial: What Is… Aperture?