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Aperture
Definition
Most cameras have some kind of lens. The purpose of the lens is to collect light and focus it onto the film or digital sensor of the camera. As well as focusing the light the lens can usually also control the amount of light that hits the sensor. It does this by having an aperture. The aperture is typically a group of metal petals that open or close to allow more or less light through.
Comments / Tips / Experiences
Aperture sizes are described as “f-stops” or “f numbers”. Larger f numbers describe smaller apertures and vice versa. So f/1.4 (f-stop 1.4) would be a very large aperture that lets in lots of light. f/22 would be a small aperture that lets in only a little light. This would probably cause the camera to choose a longer shutter speed.
Most point and shoot and SLR cameras have automatic aperture selection but many of the more expensive cameras also have special modes that allow the photographer to choose the aperture they want. In this way the photographer can control depth-of-field in the picture. The different f-stops in the aperture range translate to how much light reaches the sensor in any given shot. Going up (smaller number) in aperture by one f-stop allows twice as much light to reach the sensor. So a picture shot at f/5.6 will receive twice as much light as the same shot at f/8. Also, going up (smaller number) in aperture produces a more shallow depth of field (dof). Thus, an f/1.4 will let a lot of light in to the sensor on each shot, but will have a very narrow depth of field.
