>"Changes in millimeters [focal length] make less and less difference in
>angle of view as you approach zero."
>
>You have this backwards. Angle of view increases quite rapidly as you
>decrease the focal length.
Sorry, you're absolutely right. What I was trying to illustrate is that it
is a hyperbolic relationship, that approaches, but never reaches, its
limits. You can never have a 180 degree rectilinear, nor a 0 degree one.
Thus making lenses gets asymptotically (approaching infinitly) more
expensive as one tries to make a lens closer to 180 degrees or 0 degrees.
I've published a chart of focal lengths vs angle of views for 1mm to 599mm
in two mm increments, along with three graphs showing the relationship,
which makes it easier to visualize. The first graph is the total range,
which describes a hyperbola, the other two are expanded ranges. This is a
small (25kb) PDF download.
<http://www.bytesmiths.com/stuff/Length-Angle.pdf>
I can make the original available to anyone who has ClarisWorks. (Sorry,
Excel users -- this is a Microsoft-free zone...)
: Jan Steinman <mailto:jans@xxxxxxxxxxx>
: 19280 Rydman Court, West Linn, OR 97068-1331 USA
: +1.503.635.3229
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