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Film - Digital

What is the camera aperture?

In photographic terms an aperture is simply a hole that lets light through the light tight housing. This might be as simple as a fixed pinhole in a tin to a variable opening in a complex glass lens controlled through and automatic exposure system.


In both film and digital capture, the aperture is a mechanical means of controlling  the flow or amount of light through the lens to the film or in the case of digital the CCD, to make the exposure on the light sensitive material or receptor. This is usually done through a series of fine over lapping blades that can be controlled to create smaller or larger openings by rotating a ring on the outside of the lens. In some situation this can be set manually in a physical manner, digitally in a manual manner through a control on the camera, or automatically by the electronics in the camera.

The essential as aspect to understand is it is an opening that can be varied in size to allow different amounts of light through the lens.

The aperture has settings that are measured in f stops  - the larger the f stop number the smaller the opening. While it might seem strange that this is the case and the f stop numbaers run in a funny sequence - there is a reason for this.

The range of f stops is as follows:

Open or wide apertures
stopped down or closed apertures
f l fl.4


f2.8 f4 f5.6


f11 f16


f32  f45 f64
Sometimes it is useful to think of the aperture like the pupil or iris in our our, where in light conditions it closes up while in dim conditions it opens to let more light in



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