Telescope, CCD and Eyepiece Calculator - Deep Sky Watch
Lowest and highest useful magnification - Optics Trade Blog
Focal length, explained by RP Photonics Encyclopedia; focal distance, dioptric power, curved mirror, lens equation, microscope, photographic objective, focus, beam radius
Optics for Astronomy
Thiery Legault - How to adjust the focal length ?
Cassegrain formulas.
How does one calculate the total angular magnification of a telescope given only the focal length? - Quora
Tele Vue Optics: Imaging Methods
Thiery Legault - How to adjust the focal length ?
Telescope Equations: Minimum Magnification
Telescope Magnification Calculator - Calculator Academy
Telescope Equations: Magnification
Refractive Telescopes
Simple Formulas for the Telescope Owner - Sky & Telescope - Sky & Telescope
Focal length - Wikipedia
Tele Vue Optics: The Majesty Factor
Refractive Telescopes
Telescope Magnification Calculator
Formula to estimate exposure from aperture & F ratio - Beginning Deep Sky Imaging - Cloudy Nights
NASA - Build a Telescope
Light Vortex Astronomy - Article: How to Very Accurately Calculate your Telescope's Effective Focal Length
Two-mirror telescope aberrations
