Brian Ventrudo

Schmidt-Cassegrain Telescopes

May 14, 2020 by Brian Ventrudo Filed Under: Astronomy Equipment

A Schmidt-Cassegrain telescope (credit: Celestron)

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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A Primer on Telescope Mounts

May 3, 2020 by Brian Ventrudo Filed Under: Astronomy Equipment

A professional-grade German equatorial telescope mount (credit: Bisque.com)

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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Edge-On Spirals Galaxies in the Northern Spring Sky

April 30, 2020 by Brian Ventrudo Filed Under: Deep Sky

A close-up of NGC 4565 (the Flying Saucer Galaxy), an edge-on spiral in Coma Berenices. Image credit: ESO.

The great amateur astronomer Leslie Peltier once suggested a cure for many of the world’s problems is simply “one gentle dose of starlight to be taken each night just before retiring”. If you feel the need for a little starlight these days, there is no better bang for your buck than looking at galaxies. Northern spring is the perfect time for observing these immense collections of billions of stars, hundreds of which lie within easy reach of a small telescope (thousands if you’re using a camera instead of an eyepiece) [Read more…] about Edge-On Spirals Galaxies in the Northern Spring Sky

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Ten Things to Know and Do Before You Buy a Telescope

April 23, 2020 by Brian Ventrudo Filed Under: Astronomy Equipment

MCT-266x300 Binoculars are inexpensive, simple and easy to use, and yet bring in thousands of objects within our own Milky Way Galaxy and beyond. As you learned in the last article in this series, every stargazer should own a pair.

But there may come a time when you want to see more, when you want to see objects brighter and bigger and farther way. That’s when you want to consider a telescope.

A short word of advice here first…

Many beginners who buy a telescope before learning the basics of what to see in the sky (and how to see it) usually get frustrated and give up astronomy before they barely get started. It’s like someone who wants to learn to sail starting out on a 40-foot three-masted schooner. It’s just too complicated and it leads to frustration. By learning a little background first, new stargazers can make their experience with their first telescope rewarding, and quite frankly, life changing (in a good way).

So how do you know if you’re ready to buy and use a telescope? Here’s a subjective list of 10 things you need to know and do before you take the leap into telescopic observing [Read more…] about Ten Things to Know and Do Before You Buy a Telescope

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How to Choose Astronomy Binoculars

April 12, 2020 by Brian Ventrudo Filed Under: Astronomy Equipment

A pair of large 15x63 binoculars for astronomy (Credit: Orion Telescopes) — A pair of large 15×63 binoculars for astronomy (Credit: Orion Telescopes)

Every stargazer needs a pair of binoculars. Unlike most telescopes, binoculars are easy and intuitive to use. They produce a right-side-up image and a large field of view, which makes it easy to aim them at an object and find what you’re looking for. And they don’t need any time to set-up and align. You just grab them and head outside under the stars. Binoculars are especially useful for seeing large craters on the Moon, the moons of Jupiter, the occasional comet, close groupings of the Moon and planets at sunrise and sunset, and, once you know how to find them, larger star clusters and groupings of stars all over the sky. In this article, you learn how to choose and use a reasonably-priced pair of binoculars for astronomy [Read more…] about How to Choose Astronomy Binoculars

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