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Shooting Modes I — Aperture Priority Mode

February 4, 2009

Aperture Priority is a setting that allows the user to choose a particular aperture value whereas the camera can select a matching shutter speed. These two factors ensure optimum exposure. The primary function of using this mode is to control the depth of field. The depth of field is defined as the portion of a scene that contributed to the sharpness of the image. In case of landscape images a larger depth of field is required while a smaller depth of field is more apt for portraits and wildlife etc. This DOF is determined by the subject distance, the focal length and the aperture. The depth of field and aperture are inversely proportional to each other. The smaller the aperture the larger is the DOF and vice versa.

Ideally the aperture adjusts the size of the opening through which light passes through the camera's image sensor. Thus in case the aperture is small it indicates that less light reaches the image sensor and delivers darker images. Whereas higher aperture means more light reaching the image sensor thus delivering brighter images.

Aperture Priority mode is not a relatively new concept, it was incorporated even in the traditional and earliest cameras in a much simpler and easier way.

The aperture also has a part to play in the sharpness of an image like the shutter speed. With the change in the aperture there occurs a change in the depth of field which eventually affects the sharpness of an image. For example, in case of landscape photos a larger DOF is required thus a smaller aperture is used. This results in the entire image being sharp, however in case of portraits the DOF is small, aperture is large, thus only the subject that is in focus is sharp while the background will be considerable softer.

Aperture settings are called f-stop and these actually indicate the size of the aperture opening. The standard lens on a digital camera will range from about f/2 to about f/16. As the f-stop gets larger the aperture size gets smaller, it will be easier to remember this if f-stop is considered as a fraction. A Fast Lens is defined as a lens that can be opened to a wide aperture for the given focal length. For example a a lens with a maximum aperture of f/1.6 opens wider as compared to the one that has a maximum aperture of f/2.8. Faster lenses are useful when you need to photograph in low light surroundings or while shooting fast moving images like a sports event.

Aperture of f11.4 Aperture of f4.0

Written by digicam · Filed Under Article 

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