Autofocus refers to a camera’s ability to automatically adjust and focus its lens on a framed image. It functions by using a number of focus points to zero in on the object; then, small motors automatically position the lens into proper focus. The number of focus points a camera is capable of generally increases the more expensive the camera is.
Cameras can come equipped with one of two types of autofocus systems: a passive autofocus or an active autofocus. While the passive mechanism uses sensors to detect contrasting light, active autofocus uses timed lasers to calculate the image’s distance and then adjust the lens accordingly.
Nearly all digital cameras today are equipped with an autofocus and a manual focus mode.
Although Pentax ME-F first developed autofocus in 1981, it didn’t become a standard feature on consumer cameras until 1985. However, not all consumer camera manufacturers embraced the autofocus mechanism. While Cannon and Minolta immediately made autofocus a feature of their camera, Nikon and Pentax resisted. To this day, both Nikon and Pentax continue to produce manual cameras.
Pictures taken with a camera on autofocus, however, can lack some of the features associated with manual camera photos. Experts tend to agree that photographs taken with autofocus have poorer definition and lack continuous color in their depths of field. Similarly, cameras with autofocus generally have less aperture settings. Consequently, autofocus can limit the degree to which a photographer can manipulate his pictures.
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