BetterPhoto Q&A
Category: New Answers

Aperture

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March 15, 2005

I will attempt this... someone can correct me on any technical points I miss..

The aperture controlls the amount of light by controlling the size of the opening that allows light in to hit the recording medium (film or sensor). A larger aperture, allows more light. The pre-determined places that the aperture can 'stop' are referred to as 'f-stops'. f2.8, f4, f5.6 etc.
This is where it gets confusing, esp. to new people. The smaller the f-stop number the larger the opening. It is an inverse relationship. So an f2.8 is a larger opening than an f4. Each full f-stop increment lets in 1/2 the light of the previous f-stop. (beware here, a lot of cameras now have 1/3 or 1/4 f-stop increments). If my memory serves me right, f2.8 to f.4 is a full stop, meaning that at f2.8, twice as much light is let in than at f4.

The shutter, by comparison, controls how long the light is allowed in.

Hope this helps,
Robert

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March 15, 2005