# Talk:Field of View

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in the formula $FoV = 2 * atan \frac{35}{2 * Focal Length}$

The "35" should be some "length" because it is divided by a length, and should become unitless. Of course the length is the size of a standard negative: 35mm. If you want to "ignore units" as most americans like to do, it should not that "Focal length" is in mm. But more accurate is:

$FoV = 2 * atan \frac{35 mm}{2 * Focal Length}$