Ron Wodaski's CCD Calculator Download: Downloads CCD images from outer-space and allows beginner astronomers analyze and view planets, stars and galaxies with the help of telescopes
Telescope, CCD and Eyepiece Calculator - Deep Sky Watch
Simple Formulas for the Telescope Owner - Sky & Telescope - Sky & Telescope
Telescope With Calculator And Pencil Stock Photo - Download Image Now - Analyzing, Astronomy, Balance - iStock
Focal Length Lens Calculator - Ricoh International B.V.
Lens Calculator - PowerPhotonic
Telescope, CCD and Eyepiece Calculator - Deep Sky Watch
DobSTUFF - Complete Telescopes or Wood Parts for your Optics