What's a Lens F-Ratio and How is it Determined?
f-number - Wikipedia
Focal length in detail - Beginners Forum (No Astrophotography) - Cloudy Nights
Image Resolution: Effect of Focal Ratio - Beginning Deep Sky Imaging - Cloudy Nights
The Big Red One: My Optimized 6-inch f/9 Reflector - Gary Seronik
Newtonian Reflecting Telescope Designer
Focal Ratio of a Telescope, Explained - The Alien Tech
Basics Part 1: Understanding Aperture, Focal Length and Focal Ratios – Blackwater Skies
Basics Part 1: Understanding Aperture, Focal Length and Focal Ratios – Blackwater Skies
Focal Ratio of a Telescope, Explained - The Alien Tech
Simple Formulas for the Telescope Owner - Sky & Telescope - Sky & Telescope
focal ratio - Society for Popular Astronomy
h-alpha and white light sun images
Focal Ratio vs. Aperture: What Makes an Object Look Brighter Through a Telescope? - Sky & Telescope - Sky & Telescope
ZipDob - the Zip Dobsonian - Mel Bartels
f-number - Wikipedia
Telescope Focal Ratio Explained - YouTube
Photography 101 - Lenses, Light and Magnification
Astrophotography, Pixel by Pixel: Part 2 - Focal Ratio Effects – Cloud Break Optics
Lecture 3
Choosing a Telescope for EAA
What's a Lens F-Ratio and How is it Determined?
Telescopes: Focal ratio, plane and telescope types - YouTube
Aperture, focal length and focal ratio - Optics Trade Blog
