Exactly how I calculated my theoretical lens series.
Moose
John A. Lind wrote:
My Bad on my original posting of 150mm. I therefore retract it. For
rectilinear lenses, Angle of View is directly proportional to the
arctangent of the ratio of film dimension to focal length. Now that
I've spewed the basic relationship out in text form that only a
Mathematician or Physicist can decipher, here it is in equation form
using ASCII characters:
FOV = 2 * arctan( 0.5 * X / f )
FOV = Field of View
X = film dimension (can be horizontal, vertical or diagonal)
f = lens focal length
To find a focal length for a specific field of view, rearrange this
equation and the focal length for a particular film dimension and FOV
becomes:
f = 0.5 * X / [2 * tan( FOV / 2)]
Thus, for field of view, approximately 135mm is half-way between 100mm
and 200mm.
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