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[Lesson 2] Auto Exposure Modes (Av, Tv & P)

There are three modes on Canon DSLR cameras that automatically calculate the appropriate exposure: the Aperture-priority AE (Av) mode, Shutter-priority AE (Tv) mode, and Program AE (P) mode. The camera calculates the optimal value with the use of a highly-controlled algorithm to provide reassuring support for a pleasant shoot. (Reported by: Ryosuke Takahashi)

Aperture-/Shutter-priority AE Modes & Fully Automated Program AE Mode

The auto exposure mode is designed in such a way that the shutter speed and aperture value are determined automatically by the camera to obtain optimal exposure. In the "Shutter-priority AE mode" and "Aperture-priority AE mode," the photographer sets one of the two values the shutter speed or the aperture, leaving the camera to decide the value of the other.

In the Program AE mode, the camera uses a more highly-controlled algorithm to calculate and determine both the shutter speed and aperture value. The multiple auto exposure mode offers different features to support a wide array of shooting styles.

In Aperture-priority AE mode for example, the photographer is able to select an aperture value which enables him to control the background blur in his picture.

On the other hand, Shutter-priority AE mode gives the photographer control of how he wants to capture moving subjects. Not only do the aperture and the shutter act as valves for adjusting the amount of incident light that enters the camera, they have an impact on the overall output of the image.

Types of AE Modes

[Av] Aperture-priority AE mode

The photographer sets the aperture value and the camera determines the shutter speed. Ideal for subjects with minimal movement.

Suitable for:

  • Portraits
  • Landscapes

[Tv] Shutter-priority AE mode

The photographer sets the shutter speed and the camera determines the aperture. Ideal for expressing motion.

Suitable for:

  • Sports
  • Animals

[P] Program AE mode

In this mode, the camera automatically determines both the shutter speed and aperture value. The brightness of the subject and the lens type are also taken into account in the consideration.

Suitable for:

  • Snapshots
  • Commemorative photos

Selecting and operating the AE modes

(1) Select a mode using the Model Dial

Select a mode using the Mode Dial simply by aligning the index with "Av," "Tv," or "P."

(2) Turn the Main Dial to adjust the setting

In the Av or Tv mode, adjust the aperture value or shutter speed respectively using the Main Dial.

Display on the LCD monitor

The selected mode is displayed on the LCD monitor in the area indicated by the red frame.

Trivia – When do you use the M mode?

The M (Manual) mode allows the photographer to have full control of both the aperture value and shutter speed. This mode comes in handy in genres such as studio photography, where you want to adjust the light of large flash units individually, or when you do not wish to be restricted by the built-in exposure meter of the camera. It is also frequently employed for night and sports photography.

Ryosuke Takahashi

Born in Aichi in 1960, Takahashi started his freelance career in 1987 after working with an advertising photo studio and a publishing house. Photographing for major magazines, he has travelled to many parts of the world from his bases in Japan and China. Takahashi is a member of the Japan Professional Photographers Society (JPS).