On Mon, 02 Jan 2006 18:42:00 -0600, David Knisely
wrote:

+Unfortunately, this formula (like so many other amateur-derived
+formulae) does not yield results which are quite as close to reality as
+the somewhat simpler (and more commonly used) Eyepiece Field Stop formula:
+
*******

amateur derived formulae????? Where do you get off making that
statement?


+TFOV = (180/Pi)*(EFSD/Fl)
+

What are you calculating? The system or the apparent field of view of
the eyepiece. To me it looks as if you are deriving some equation for
the system. This is deduced from the FL as teh focal length of the
telescope. The formula that I am using calcualtes the apparent field
of view of the eyepiece. Not eyepiece and telelscope.

+where Pi is the usual 3.1415926... EFSD is the eyepiece field stop
+diameter, Fl is the telescope focal length, and * is short hand for the
+multiplication operation (the division operations in parethesis are to
+be done first). In most cases, the 180/Pi (the number of degrees in one
+Radian) can be just rounded to 57.3 (although for a few review tests, I
+have had to use 57.296 when doing accurate measurement comparisons).
********

Please. I do not need a lecture on mathematics.

james