Canon 30D1785, 30D28135, 9337B001 manual Aperture value, CF CompactFlash Card, Depth of Field, 130

REFERENCE

Basic Terminology for Digital Cameras and Digital Photography

AE

Auto Exposure is a function that calculates the exposure automatically. The camera has a built- in exposure meter that automatically determines the correct exposure (the combination of shutter speed and aperture value).

AF

Auto Focus is a function that focuses the camera automatically.

Aperture value

The lens aperture opens and closes to control the amount of light that reaches the imaging element. The aperture value (or f-number) is equal to the focal length divided by the aperture diameter. The aperture value is displayed on the camera’s LCD panel and in the viewfinder, and ranges from 1.0 to 91, depending on the particular lens mounted on the camera.

CF (CompactFlash) Card

CompactFlash card is the storage media used to record photo images taken by the EOS D30.

Depth of Field

When a subject is in focus, a distance in front of and behind the subject is also in focus. This is called the depth of field. The greater the aperture value (that is, the smaller the aperture), the broader the depth of the field. This is called a deeper depth of field. Conversely, the smaller the aperture value (larger aperture), the narrower the depth of field, called a shallower depth of field.

The depth of field is affected as described below:

qA smaller aperture (larger aperture value) increases the depth of field. Thus, reducing the aperture provides a deeper depth of field.

wAt a given subject distance and aperture value, a lens with a shorter focal length increases the depth of field.

Thus, a wide-angle lens gives a deeper depth of field than does a telephoto lens.

eAt a given aperture value, a greater distance between the camera and subject increases the depth of field.

rWhen the optimum focus is on the subject, the depth of field behind the point of optimum focus is longer than the depth of field in front of the point of optimum focus. The depth of field is normally twice as deep behind the subject as before the subject (see illustration).

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