The Advantages and Disadvantages of Stopping Down a Lens – Sunex Inc.
stopping down aperture to increase focal ratio - Beginners Forum (No Astrophotography) - Cloudy Nights
astronomical optics, part 3: the astronomical image
Does a high aperture mean more focus? - Quora
HEXEUM Computerized Telescope 105mm Aperture 950mm Fully-Automated Tripod Easy To Use And Break Down Hight Technology Tripod - Easy To Carry on Galleon Philippines
astronomical optics, part 2: telescope & eyepiece combined
What determines a telescope's fstop? I often see the same size lens with different fstops. - Quora
Stopping down - Wikipedia
Why and how to make a sub-aperture mask for a refractor | 10 Minute Astronomy
Hobby Killers: What Telescopes Not to Buy - Sky & Telescope - Sky & Telescope
The A to Z of Photography: Aperture | TechRadar
Aperture and Field Stops - YouTube
stopping down aperture to increase focal ratio - Beginners Forum (No Astrophotography) - Cloudy Nights
Optical terms and conventions
Can you get sharper images by stopping down your scope with a cardboard mask? - Sky & Telescope - Sky & Telescope
Fun with a 5" off-axis aperture mask - why bigger isn't always better. : r/ telescopes
Photography Jargon – NPC Main
APERTURE MASK GIVES ME TWO TELESCOPES - Page 3 - Refractors - Cloudy Nights
Why and how to make a sub-aperture mask for a refractor | 10 Minute Astronomy
The Advantages and Disadvantages of Stopping Down a Lens – Sunex Inc.
Early telescopes
F-number - Wikiwand
astronomical optics, part 2: telescope & eyepiece combined
Does an off-axis aperture equal an Apo of same size? - Reflectors - Cloudy Nights
Newtonian Reflecting Telescope Designer
The Advantages and Disadvantages of Stopping Down a Lens – Sunex Inc.
