Friday, September 25, 2009

Aperture: What is it?

Every profession has its own lingo. It is the same with photography.  Photographers say things like, “Use a wider aperture,” or, “What f-stop are you using?”  So, What is an f-stop?  It is a term for a measurable expression of how much light is entering a camera lens. Aperture is the same thing as an f-stop.
All cameras have a lens which light passes through to help record the image. However, to get a proper exposure so you do not have underexposure or overexposure, light must come in through the lens in the  amount needed.   That is, the photo should be neither too light nor too dark. The f-stop on a camera helps control the exposure.
The “F” in f-stop stands for focal length.  The focal length divided by the diameter of the pupil , or the amount of light entering the lens is how the f-stop is determined. The numbers f/2 or f/16 are expressions of  f-stops.   The number denotes how wide  the opening in the aperture is.  The aperture  is an opening behind the camera lens. The aperture works like the pupil of the eye. It gets wider when there is not a lot of light and smaller when there is more light. Test this out. Get a flashlight and go to a mirror. First look into the mirror at the black part or pupil of your eye. Notice the size. Now turn on the flashligtht and point it at your eye.  While looking in the mirror you will notice that your pupil gets smaller. This is exactly how an apeture works.  The more light, the smaller the pupil of your eye, the less light the wider the pupil of your eye.  Now here is the weird part. When you apeture is open wider, the f-stop will be a small number like f/5.6 or f/2(if you have a fast lens).  If the apeture is smaller, you will have a number like f/16 or f/22.
Now that we have learned a little about apertures and f/stops we need to know about shutter speeds.  To get the proper exposure we need to have an apeture and a shutter speed that correspond.  For instance, you can use a wide apeture or f/stop (which will have a small number) and fast shutter speed, or a narrow f-stop (larger number) and a slower shutter speed. When these correspond the result is a properly exposed photograph. Shutter speeds are measured in amounts of time. For example, you can have 6th of a second or a longer exposure of 1 second.  1 second will let in more light than 6th of a second. To get the proper exposure you will balance the f-stop and the shutter speed.
Now, when you’re out shooting and you hear another person say, “What f/stop are you using?” you will know what to say.
If you need clarification or more help understanding this let me know. Thanks, Brian.
aperture copy

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