How to Set the Aperture on a Digital Canon Rebel


Using aperture selectively opens a number of creative options for every photographer. Any of Canon's EOS Rebel line of cameras features several ways to set aperture, in both manual and program modes. This article runs through these using Canon's EOS Rebel T5i, called the flagship model of the company's DSLR camera line, but many settings and controls are the same regardless of Rebel model. While still photography is described here, the settings are similar when shooting video on Rebel models with that capability.

Manual Mode

Step 1

Select M on the Mode Dial to choose manual operation. This gives you complete control over the camera's settings. The Mode Dial is on the top right of the camera as you hold it to take a photo.

Step 2

Set the aperture by pressing the Av +/- button located on the rear of the camera to the right of the LCD screen, and by simultaneously rotating the wheel on the top of the camera above the shutter button. The effects of changed aperture settings follow these general guidelines:

  • Small Aperture number: larger aperture opening allowing more light and resulting in a shallow depth-of-field.
  • Large Aperture number: smaller aperture opening allowing less light with a deep depth-of-field.

The range of aperture is dependent on the attached camera lens since the aperture diaphragm is located in the lens, and the aperture number, also called the f-stop, depends on the length of the lens divided by the size of the aperture.


  • When you change aperture settings, you also need to adjust other settings related to exposure, including shutter speed and ISO sensitivity. Along with aperture setting, these three elements balance exposure.

Aperture Priority Mode

Step 1

Select Av on the Mode Dial to select aperture priority mode. In this mode, when you change the aperture setting, the camera changes the shutter speed automatically to maintain balanced exposure.

Step 2

Set the aperture by rotating the wheel on the top of the camera above the shutter button.

Scene Program Modes

Most EOS Rebel cameras include program modes optimized for different photographic applications. Canon calls these Basic Zone modes and while you can't change the settings of these modes, understanding them permits quick selection of aperture function in an automatic program. Here are some examples common to most Rebel cameras.

Portrait Mode

Select this by choosing the woman's profile icon on the Mode Dial. Your camera will use a wide aperture setting to blur the background behind the subject. Since a wide aperture permits more light to pass, the camera's program will set a faster shutter speed to compensate.

Landscape Mode

Choose the mountain icon on the Mode Dial for landscape mode. This program uses a narrow aperture to maximize depth-of-field, so the shutter speed will be slower to compensate.

Close-Up Mode

Select the flower icon for close-up mode. From an aperture standpoint, close-up mode and portrait mode are similar, designed to use a wide aperture with shallow depth-of-field to help isolate the subject. Other program controls in this setting optimize camera performance for subjects close to the camera.

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