Camera Aperture Basics

Aperture and other technical photography basics can induce yawns in the most eager of budding shutterbugs, but once these basics are understood, the rest of photography easily comes into focus. Aperture, ISO, and shutter speed are all important terms to know, whether you have a point-and-shoot or a professional camera. This article explains aperture and provides tips for using it to create better photographs.

photography aperture basics

Photo by Alex; ISO 1250, f/5.6, 1/30-second exposure.

To better understand aperture, think about how the irises of your eyes get bigger and smaller to allow more or less light into the pupil. Like your irises, the camera’s lens diaphragm widens and narrows to let in more or less light. Thus, the aperture dictates the exposure (the darkness or brightness) of the photo. The aperture also has another important function which we’ll look at shortly.

Aperture refers to the size of the camera’s lens diaphragm and is measured in F stops. The smaller the F Stop number, the wider the aperture. This is where it is easy to get confused. Actually the F stop numbers represent ratios, which is why the larger the F stop number, the smaller the aperture.

Depth of Field

Besides controlling light, aperture controls depth of field. To better understand this, make a fist and hold it in front of your eye. Now slowly open your hand. See how the focus changes as you open your hand? Sure you can see more through the bigger opening, but when the opening in your fist is small everything is in focus? Try it again and see how when you open your fist, the object closest to you will come into focus while objects further away will be fuzzy. This is how aperture determines depth of field or how much of a picture is in focus.

photography aperture tips

Photo by Thomas Hawk; ISO 250, f/3.2, 1/320-second exposure.

If you are shooting in auto mode, the camera will set exposure and aperture and attempt to focus on what it perceives to be the main subject of the photograph, but the results may not be what you want.

For this reason, many cameras have an Aperture Priority setting to help eliminate this problem. This allows you to set the aperture and then it automatically adjusts the shutter speed to compensate for the aperture. For example, if you set the aperture for a landscape, this narrows it, thus letting in less light. The camera would then automatically increase the amount of time the shutter stays open so that your photo isn’t underexposed or too dark. Aperture Priority isn’t exact, but this is how it usually works.

Now if you have a DSLR and are taking pictures in manual mode, you can adjust the shutter speed and aperture separately.

basic tips for photo aperture

Photo by orientalizing; ISO 100, f/5.6, 1/640-second exposure.

Preset Modes

Most compact cameras have preset modes such as landscape, sports, or portrait. When the mode is set to landscape, the aperture automatically narrows to bring everything into focus. At the same time, the shutter speed automatically slows, thus leaving the shutter open longer to compensate for the lessened amount of light streaming through the diaphragm.

When you switch to portrait mode and focus on a person in front of you with the landscape in the background, the camera brings your subject into focus, making the person stand out more than the landscape. And it will speed up the shutter speed so the photo isn’t overexposed by the extra light allowed in with the larger aperture.

Remember: the smaller the aperture, the greater the F stop number (because it represents a ratio, not a whole number) and the greater the depth of field.

f stops and aperture explained

Photo by Several Months; ISO 200, f/2.8, 1/640-second exposure.

Understanding photography basics like aperture is not only important for those using manual settings or Aperture Priority, it also helps those using preset modes. Here are three preset modes you should better understand:

  1. Portrait: How much the background blurs when using this mode depends on your camera and the distance between your subject and background – a minimum of 10 feet works best. This mode can be used for any subject you want to bring into focus while taking the background out of focus.
  2. Landscape: (called “Infinity” on some cameras): This is the mode depicted by the mountain peak or figure 8. You can use this when you want everything in the picture to be in focus, such as seascapes, cityscapes, or your garden.
  3. Macro: This mode, depicted by the tulip, opens the camera’s aperture extra wide so that you can take extreme closeups without the blur caused by not enough focus. Depending on your camera, you’ll be able to get anywhere within an inch to a foot of your subject. Remember to focus on the subject that you want in focus, whether it be a caterpillar’s eyes or a butterfly’s wings.

Just applying this knowledge can help you take some beautiful photos that you’ll be proud to display in your home.

About the Author:
Autumn Lockwood is a writer for Your Picture Frames ( and loves taking pictures. Your Picture Frames makes it easy for you to find just the perfect frame for your photo or artwork.

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