Aperture

Posted: January 11, 2012 in Uncategorized
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Aperture is the hole inside the lens created by the fins within the lens. This hole is used to regulate two things. First the amount of light entering the lens and passed through to camera sensor or film. Second, aperture is used to control the depth of field within an image. In other words, it’s used to control the amount of area within focus. Aperture is measured in stops or f-stops. The stop scale, in full stops, goes like this: f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/45 & f/64.

Most consumer or kit lenses, which are usually zoom lenses, start around f/3.5 or f/5.6 and goes to about f/22 and can cost anywhere from $50 to around $400. Entry level prosumer lenses typically range from f/2.8 to f/32 and can range from $150 to about $1800. Pro level lens can go from one end (f/1) to the other (f/64) but not on the same lens. For instance and f/1 lens which is very expensive and rare can typically go from f/1 to f/16. These lenses are used for low light. On the other end, lenses used in landscape shots might have a range from f/5.6 to f/45 or f/64. But either of these pro lenses on either end of the scale typically cost many thousands of dollars.

To sum it up, f/1 lets in the most amount of light but gives the least amount of depth, f/64 lets in the least amount of light while giving the most depth of field. Each of these stops represents half the light of the previous stop. So if you go from f/4 to f/5.6 you are allowing only half the light in. If you go two stop like from f/4 to f/8  it allows 1/4th of the light, three stops like from f/4 to f/11 would be 1/8th of the light and so on. The same goes for going the other way but the light is doubled instead of halved like f/11 to f/8 is twice the light and f/11 to f/5.6  is 4x the light. You will need to compensate for the loss or addition of light if you adjust your f/stop. This compensation can come from one of two places or a combination of either a longer/shorter shutter speed or increasing/decreasing the ISO.

Depending on what look you are trying for you can determine what f-stop to use. For example, if you are trying to focus on a single athlete in a crowd you might want to try a shallow depth of field like f/1.8 to f/2.8. If you want to capture many elements within your frame you’ll need to increase the depth of field by using a smaller f/stop like something from f/8 to f/32.

A shallow depth of field can also be used to help separate the subject from the background and/or foreground as in the photo shown above. A good way to get used to the differences in f-stop setting is by setting your camera to AV (aperture priority). Try this and play around with it for a while until you get a good feel of what’s going on. A few things to keep in mind are: the larger the aperture(like f/2.8) which equals less depth of field, the faster the shutter speed, the smaller the aperture (like f/16) equals more depth of field but requires a slower shutter speed(easier to blur). Also keep in mind the shutter speed can be increased/decreased with the ISO.

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Comments
  1. ebosman12 says:

    Great post, Jeff! It was full of detail. I feel like if I was handed a camera I would actually know how to do something with it haha. Keep the great information coming!

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