Exposure (photography)

In photography, exposure is the amount of light per unit area (the image plane illuminance times the exposure time) reaching a photographic film or 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 (EV) and scene luminance in a specified region.

In photographic jargon, an exposure generally refers to a single shutter cycle. For example: a long exposure refers to a single, protracted shutter cycle to capture enough low-intensity light, whereas a multiple exposure involves a series of relatively brief shutter cycles; effectively layering a series of photographs in one image. For the same film speed, the accumulated photometric exposure (H_v) should be similar in both cases.

Definitions

Underexposure and overexposure

A photograph may be described as overexposed when it has a loss of highlight detail, that is, when important bright parts of an image are "washed out" or effectively all white, known as "blown-out highlights" or "clipped whites". A photograph may be described as underexposed when it has a loss of shadow detail, that is, when important dark areas are "muddy" or indistinguishable from black, known as "blocked-up shadows" (or sometimes "crushed shadows", "crushed blacks", or "clipped blacks", especially in video). As the image to the right shows, these terms are technical ones. There are three types of settings they are manual, automatic and exposure compensation.

Rebecca Black

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Rebecca Renee Black (born June 21, 1997) is an American singer and YouTuber who gained extensive media attention with the 2011 single "Friday". After the video went viral on YouTube and other social media sites, "Friday" was derided by many music critics and viewers, who dubbed it "the worst song ever". Rebecca went on to do other songs, of which her song "Saturday" sung with Dave Days earned more success. She currently uploads videos on her YouTube channel about various topics.

Early life and education

Black was born in Irvine, California. She is the daughter of John Jeffery Black and Georgina Marquez Kelly, both veterinarians. Her mother is of Mexican descent, and her father, originally from Iowa, is of English, Italian, and Polish descent. Black attended private school from kindergarten to 6th grade, and moved to a public school due to bullying. She joined the school's musical theater program, where she felt she was "meant to be." In April 2011, Black dropped out in favor of homeschooling, citing both a need to focus on her career and a desire to avoid taunts from her former classmates. Black was also failing English class due to her busy schedule.