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How auto focus works

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How auto focus works

  1. 1. How auto focus works By Amelia Bailey
  2. 2. What is autofocus(power-focus)? Autofocus can also be called power-focus because a lot of times a computer uses a miniature motor to focus on an image automatically.
  3. 3. What automatic features are included and what two types are there?  Automatic film advance  Automatic flash  Automatic exposure  Active (cheaper)  Passive (more expensive)  Some have both
  4. 4. Infrared signal uses  Triangulation  Amount of infrared light reflected from the subject  Time
  5. 5. Active autofocus  Makes flash photography much easier  Uses sound waves to tell the distance  Has problems like 1. It gets confused when you take a picture of light (birthday candles). 2. Black surface my absorb the infrared beam. 3. It may focus on something in front of the object you are trying to capture.
  6. 6. Passive autofocus  Often found in single-lens cameras.  Uses computer analysis of the image to tell the distance.
  7. 7. Out-of-focus/in-focus pictures
  8. 8. Works cited  http://electronics.howstuffworks.com/autofocus. htm

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