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Homework Help: Another focal length question

  1. May 9, 2009 #1
    Hi. If using:

    f (focal length) = a / ( 2 x arctan (theta / 2)) where a = 13 and is the Field of View

    the value I get for the focal length is 0.03 and this seems too small. Unless the calculation has not been done right?

  2. jcsd
  3. May 10, 2009 #2


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    Staff Emeritus
    Science Advisor
    Homework Helper

    Something is weird about your equation. If theta is an angle, it makes no sense to take the arctan of an angle.

    That depends. 0.03 mm would be too small. 0.03 m would actually be reasonable. 0.03 miles could be too large.

    Moral: units are an important part of the answer.
    Last edited: May 10, 2009
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