Often times you will see telescopes for sale that claim big magnifications such as up to 1000X power or 500X power telescope. 99 $129.99 $129.99 Large BAK-4 Prism inside and Fully Multi-coated Lens Coating: Strengthen the key function of a monocular, guarantee superior light transmission and brightness, make your view brighter, clearer, and delivers crisp images. An example calculation of focal ratio and magnification for a scope with a 25 mm focal length, eyepiece, 102 mm aperture, and 900 mm focal length, telescope. ; Waterproof, Dust-proof, and Shockproof Design: Nitrogen-filled waterproof and O-ring sealed optics prevent moisture, dust, and debris and ensures the living waterproof function. How to Make a PVC Telescope: Placing any two convex lenses (with different focal lengths) a distance apart will create an up-side-down magnified image of far away objects.These are instructions on how to make a simple telescope out of everyday parts (PVC pipe / magnifying lense… by Richard Berry, 8.50" by 11.00", 240 pages, hardbound, 3rd Editon published 2001, $29.95. Gskyer Telescope, 70mm Aperture 400mm AZ Mount Astronomical Refracting Telescope for Kids Beginners - Travel Telescope with Carry Bag, Phone Adapter and Wireless Remote 4.4 out of 5 stars 8,489 $99.99 $ 99 . ABOUT THE BOOK… For anyone who has ever dreamed of exploring the heavens with a telescope, Build Your Own Telescope can make that dream come true. telescope focal length / clear aperture = focal ratio For example, a telescope with a focal length of 1000mm and a 100mm (4") clear aperture has a focal ratio of f/10 (1000/100=10). And while this isn't a false claim because the telescope in reference will actually go to that magnification it is a worthless number because telescopes have definite limits to … Hubble Telescope at 10x or 100x or 1000x The other night I caught a new documentary, “Hubble’s Amazing Universe” on the National Geographic Channel that in high definition wonder showed how the Hubble Space Telescope revolutionized astronomy since 1993.