Basic astronomy and night sky information
Telescopes, binoculars, and accessories for amateur astronomy.
Small Maksutov-Cassegrain telescopes are a godsend for urban observers who need a compact scope with good optics. And “Maks” are back in style, so there’s a good selection on the market. But Maks aren’t for everyone. Here’s how to tell if a Mak is right for you [Read more…] about Maksutov-Cassegrain Telescopes
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When the members of the great unwashed masses think of an astronomical telescope, they usually think of a refractor. With a large glass objective lens at the top of the tube and an eyepiece down at the bottom, refractors are the most robust and conceptually simplest type of telescope. They offer amazingly crisp views of the Moon and planets and double stars. But they are not for everyone. This short article goes through the pros and cons of refractors for astronomy and helps you decide if such a telescope is right for you [Read more…] about Refracting Telescopes for Astronomy
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Reflecting telescopes (or reflectors) collect light using a curved mirror at the rear of the main tube rather than a lens at the front end. Isaac Newton gets credit for inventing the first reflecting telescope in the late 17th century. He used a second small diagonal mirror to direct light out the side of the telescope to an eyepiece. His immensely practical design, now called the Newtonian reflector, is the main type of purely reflecting telescope in use today by amateur astronomers [Read more…] about Newtonian Reflectors and Dobsonian Telescopes
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In the most recent article on telescopes, you had a look at Newtonian reflectors, the oldest type of mirror-based telescope for astronomy. Newtonians, as you learned, have one big drawback: they are big. Because they use a single primary mirror to direct light back to a flat secondary mirror, which in turn reflects light to the eyepiece at the side of the tube, the physical length of a Newtonian is roughly equal to its focal length. So a 12″ aperture f/6 Newtonian, for example, is at least six feet long and more than a foot wide. But in 1672, shortly after Issac Newton developed his famous design, an obscure French Catholic priest named Laurent Cassegrain invented a reflector that used two mirrors to fold a long optical path into a much shorter tube. Now many reflectors, and nearly all professional astronomy telescopes, use some variation of the Cassegrain design [Read more…] about Schmidt-Cassegrain Telescopes
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Even the most expensive and carefully crafted telescope isn’t worth much if it’s not on a solid and stable mount that lets you accurately point it anywhere in the sky. A good telescope mount is as important as the optics of a telescope, and it must be sufficiently solid and stable such that if you give the telescope tube a good tap on the side, the mount should damp down vibrations in less than 5 seconds (max), and faster if you’re planning on astrophotography. Most telescopes, especially scopes aimed at beginners, include a mount when you buy them. Smaller telescopes, especially high-end refractors, may just have mounting rings or plates which allows them to be attached to a mount which you buy separately. And if you are contemplating astrophotography, a solid mount is a must-have.
All telescope mounts can be classified as one of two types: alt-azimuth or equatorial. Let’s have look at each [Read more…] about A Primer on Telescope Mounts
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