1 control Depth of field with av mode
Understand how changing the aperture affects which parts of your image are sharpest
The aperture determines how much light reaches your Canon camera’s sensor
Use Av mode on your Canon DSLR to set the aperture and control depth of field. The aperture determines how much light reaches your camera’s sensor. Measured in f/stops, values range from f/1.2 to f/32 and above, depending on your lens. The lower the number (eg f/2.8), the wider the aperture, which means more light is allowed into the camera lens, making images brighter. Conversely, the higher the number (such as f/22), the narrower the aperture, therefore less light reaches the camera sensor, causing images to be darker.
Aperture also affects an image’s depth of field (DOF). Wide apertures capture a shallow DOF, so whatever is in front and beyond your focal point will be blurry – ideal for portraits and wildlife, for instance. Narrow apertures capture more DOF, meanwhile, allowing a larger area of the shot to be sharp – ideal for landscapes when you went the whole scene in focus.
As your lens’s focal length increases, DOF decreases, even at the same apertures. So a wide focal length (eg 18mm) will capture more depth of field at f/5.6, compared with a longer focal length (eg 200mm) at f/5.6.
Control how much of a scene you want to be in focus when you take charge of aperture in Av mode