Amazon.com : Telescopes for Adults, 70mm Aperture and 700mm Focal Length Professional Astronomy Refractor Telescope for Kids and Beginners - with EQ Mount, 2 Plossl Eyepieces and Smartphone Adapter : Electronics
f-number - Wikipedia
AmScope Professional Telescope Bundle Series featuring 130mm Aperture,
focal length - Society for Popular Astronomy
What determines a telescope's fstop? I often see the same size lens with different fstops. - Quora
Everything You Need to Know Before Buying a Telescope | B&H eXplora
schoolphysics ::Welcome::
Simple Formulas for the Telescope Owner - Sky & Telescope - Sky & Telescope
How Aperture Works | HowStuffWorks
astronomical optics, part 2: telescope & eyepiece combined
Aperture, focal length and focal ratio - Optics Trade Blog
ZipDob - the Zip Dobsonian - Mel Bartels
Formula to estimate exposure from aperture & F ratio - Beginning Deep Sky Imaging - Cloudy Nights
How to Choose Eyepieces for Your Astronomy Telescope
Telescope Focal Length: Everything You Need To Know
Optical Telescopes | Let's Talk Science
Benefits of a Bigger Aperture | Celestron
schoolphysics ::Welcome::
Telescope Aperture Explained: Does Size Really Matter?
Which scope aperture is best for different kinds of objects? | Celestron
Electrowetting lens with large aperture and focal length tunability | Scientific Reports
Telescope Focal Length: Explanation - Telescope Nerd
Abrams Planetarium Telescope Information Page
Telescope stats explained - BBC Sky at Night Magazine
Astrophotography, Pixel by Pixel: Part 2 - Focal Ratio Effects – Cloud Break Optics
Secrets of Digital Bird Photography
focal ratio - Society for Popular Astronomy
