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Video:Photography: Aperture Overview

with Chris Davis

Aperture is an adjustable opening on a camera lens, which works like the iris in your eye. Learn more how to adjust aperture and how it affects photos with this helpful About.com video.See Transcript

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Transcript:Photography: Aperture Overview

Hi I'm Chris Davis for About.com.  Understanding how a cameras aperture functions will impact your overall photography.  Let's take a look at how the aperture works.

How to Adjust Aperture

The easiest way to adjust your aperture is to place your camera into the aperture priority mode.  Generally this is represented by the letters Av.

What is Aperture

Aperture works by controlling the size of the opening in the lens when a picture is taken.  It is measured in f-stops which is merely a number that represents the size of the aperture opening.  The larger the opening the more light you are allowing into the camera.  Where it gets a little tricky, is that f-stop numbers get bigger as the aperture gets smaller.  It may seem a little backwards but an f-stop of 2.8 is much larger than an f-stop 22.

How Photos are Affected by Aperture

Once you wrap your head around that concept.  It's actually a fairly simple setting to understand.  You can adjust your aperture up or down.  Moving from one f-stop to the next doubles or halves the size of the aperture opening depending on which way you make the adjustment.
 
The most immediate impact you will see by changing the aperture will be the depth of field of your photograph.  Depth of field describes how much of your image within the photograph is in focus.  A shallow depth of field, will result in one portion of your subject in focus with the foreground and background blurred.  A large depth of field will result in most of your image in focus.

In this first photo an aperture setting of f-22 was used.  You will notice that most everything from the front to the back of the scene is in focus.  This second photo the frame remained the same, however, the aperture was set to an f-top of 4.5.  Notice how the background has become blurred highlighting the subject.

Aperture for Photography Styles

In general for landscape photography you will tend to use a small aperture setting.  This will increase the focus from the foreground to the horizon.

Portrait photography, however, tends to use a large aperture to produce a blurry background.  This will keep the main focus on your subject.


A quick way to remember how aperture effects depth of field is that a small f-stop number will create a small depth of field, and large f-stop number will create a large depth of field.

To Learn more check us out on the web at About.com.  Thanks for watching.
 

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