page_title: Exposure (photography)
section_title: Automatic exposure
hierarchical_section_title: Exposure (photography) / Exposure settings / Automatic exposure
caption_attribution_description: English: House in Oltre il Colle, Italy
context_page_description: In photography, exposure is the amount of light per unit area reaching a frame of photographic film or the surface of an electronic image sensor, as determined by shutter speed, lens aperture, and scene luminance. Exposure is measured in lux seconds, and can be computed from exposure value and scene luminance in a specified region.
  An "exposure" is a single shutter cycle. For example, a long exposure refers to a single, long shutter cycle to gather enough dim light, whereas a multiple exposure involves a series of shutter cycles, effectively layering a series of photographs in one image. The accumulated photometric exposure is the same so long as the total exposure time is the same.
context_section_description: A camera in automatic exposure or autoexposure (usually initialized as AE) mode automatically calculates and adjusts exposure settings to match (as closely as possible) the subject's mid-tone to the mid-tone of the photograph. For most cameras, this means using an on-board TTL exposure meter.
  Aperture priority (commonly abbreviated as A, or Av for aperture value) mode gives the photographer manual control of the aperture, whilst the camera automatically adjusts the shutter speed to achieve the exposure specified by the TTL meter. Shutter priority (often abbreviated as S, or Tv for time value) mode gives manual shutter control, with automatic aperture compensation. In each case, the actual exposure level is still determined by the camera's exposure meter.
caption: Buildings and trees photographed with an autoexposure time of 0,005 s
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