Eyepiece Power

[Bob Agnew]

I have a question about calculating the magnification provided by a
particular eyepiece. When the aperature stop is smaller than the eyepiece
diameter, should one use the smaller or larger diameter to compute the
effective power?

[Thad Floryan]

Magnification of an astronomical eyepiece on an astronomical telescope
is simply:

Magnification = FocalLength(scope) / FocalLength(eyepiece)

See:

<http://www.astro.shoregalaxy.com/index_010.htm#3>
<http://www.astronomynotes.net/2006/06/02/calculate-eyepiece-magnification/>
<http://www.davidpaulgreen.com/tec.html>
<http://www.twcac.org/Tutorials/magnify4.htm>
etc.