How Autofocus Cameras Work

By: Gary Brown

Autofocus Video Cameras

Autofocus in a video camera is a passive system that also uses the central portion of the image. Though very convenient for fast shooting, autofocus has some problems:

  • It can be slow to respond.
  • It may search back and forth, vainly seeking a subject to focus on.
  • It has trouble in low light levels.
  • It mis-focuses when the intended subject is not in the center of the image.
  • It changes focus when something passes between the subject and the lens.

Autofocus video cameras work best in bright light. Switch to manual focus in low light.


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