Pentax KB89885 Operation Manual - Page 135
Effect of aperture, aperture
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Page 135 highlights
137 Effect of aperture The aperture increases or reduces the light beam (thickness) which passes through the lens, controlling how much light strikes the CCD. • Widening the beam by opening the aperture Objects closer and farther than the focused subject will be more out of focus. For instance, if you take a picture of a person against a landscape with the aperture open, the landscape in front of and behind the person will be blurred, emphasizing only the person. • Narrowing the beam by closing the aperture The range in focus expands forward and back. For instance, if you take a picture of a person against a landscape with the aperture narrowed, the landscape in front of and behind the person will be in focus. Appendix • When you focus on a portion of the subject, there is a range in which object closer and farther will also be in focus. This focused range is called the depth of field. 8 • As the aperture is stopped down, the depth of field (focused range) increases (wider range of focus). • Also, the wide-angle lens, and the farther away the subject, the wider the depth of field. • Zoom lenses do not have a scale for depth of field because of their structure. • The depth of field for the w differs depending on the lens but, compared to when using a 35mm camera, the value is roughly one aperture setting lower (the focused range becomes narrower). Further, check the depth of field at one stop open side for lenses with a depth of field scale.
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