Refractive Telescopes
Telescope Magnification Calculator
Thiery Legault - How to adjust the focal length ?
Two-mirror telescopes: Cassegrain, Gregorian and variants
Telescope Magnification Calculator - Calculator Academy
Light Vortex Astronomy - Article: How to Very Accurately Calculate your Telescope's Effective Focal Length
How to Choose Eyepieces for Your Astronomy Telescope
Lowest and highest useful magnification - Optics Trade Blog
Simple Formulas for the Telescope Owner - Sky & Telescope - Sky & Telescope
Telescope, CCD and Eyepiece Calculator - Deep Sky Watch
Telescope Equations
Formula to estimate exposure from aperture & F ratio - Beginning Deep Sky Imaging - Cloudy Nights
Telescope, CCD and Eyepiece Calculator - Deep Sky Watch
Telescope Magnification Calculator
Newtonian Reflecting Telescope Designer
Simple Formulas for the Telescope Owner - Sky & Telescope - Sky & Telescope
Telescope Equations: Minimum Magnification
Telescope Equations: Magnification
Focal length, explained by RP Photonics Encyclopedia; focal distance, dioptric power, curved mirror, lens equation, microscope, photographic objective, focus, beam radius
Thiery Legault - How to adjust the focal length ?
what telescope should i look for?
A Galilean telescope measures 9 cm from the objective to the eye-piece. The focal length of the objective is 15 cm. Its magnifying power is A. $2.5$ B. $\\dfrac{2}{5}$ C. $\\dfrac{5}{3}$ D. $\\dfrac{3}{5}$
astronomical optics, part 2: telescope & eyepiece combined
NASA - Build a Telescope
