Motor tracking is especially useful for high-magnification viewing and for showing celestial objects to groups of people. It's also a prerequisite for most through-the-telescope photography.
An altazimuth altitude-azimuth mount, by contrast, moves up-down in altitude and right-left azimuth. A photo tripod is an example of an altazimuth mount. Another is the popular Dobsonian mount, shown below. Altazimuth mounts are generally lighter than equatorials, in part because they don't require counterweights to balance the telescope.
I hasten to note, however, that the equatorial "fork" mounts sold with many compound telescopes are relatively lightweight, too; the photo above shows one example. Dobsonian mounts, in particular, can be very stable and low-cost. But altazimuths do not readily lend themselves to motorized operation, and you have to move the telescope in two directions simultaneously to track celestial objects as the Earth turns.
Covers all aspects of making the listed telescopes. Most astronomical atlases display all stars brighter than some specified magnitude, along with an assortment of nebulae, star clusters, and galaxies. ITEM Here's the deep truth of telescopes: It does not matter what price you pay to get into amateur astronomy. Get started now, seeing for yourself the dazzling and complex universe first opened to human sight more just years ago.
While this becomes second nature to many observers, others find it maddening. See the section below on "smart" telescopesfor a high-tech way around this problem. Your own personality should play a part in choosing a mount.
Are you comfortable with instruments that require tools and a head for numbers to set up and use? Or are you looking for the astronomical equivalent of a point-and-shoot camera? A Dobsonian can be set up in the time it took to read this paragraph. An equatorial mount can take a bit longer if you want to get the most out of its features. Computerized "smart scopes," which promise easy object-finding, are actually the most complicated to deploy. We've already covered a lot of ground in our telescope buying guide, and hopefully the tech talk you may get from a salesperson or stargazer will now make more sense.
But a few telescope buying guide topics remain before we can set you loose on your hunt. Most of us picture the big things when we think of a telescope, and those stand out in catalogs and ads. But just as you can't drive a car off the lot without the keys, there are little essentials you'll need to use a telescope to journey among the stars. By bringing light to a focus, a telescope forms an image — a little picture floating in the air inside the tube. But you need a way to view the image!
That's what eyepieces are for. Think of them as like little magnifying glasses for looking at the image. Changing eyepieces lets you change a telescope's magnifying power which equals the objective's focal length divided by the eyepiece's focal length. Every telescope owner should have several.
Eyepieces come in a bewildering variety of designs with exotic names. Generally speaking, the more expensive an eyepiece, the more lens elements it has. Most telescopes come supplied with one or two eyepieces. Ideally, you'd like to have a set that spans a range of magnifications. A Barlow lens is also worth considering: it multiplies each eyepiece's power by two or three times, effectively doubling your eyepiece collection.
A telescope buying guide tip: avoid buying a telescope that uses eyepieces with barrels that are 0. This is generally a sign of poor quality. You've got a telescope set up with an eyepiece in place. Now what? Naturally, you'll want to point it to something! Simply sighting alongside the tube may enable you to find the Moon and a few bright stars or planets. But that's all. An astronomical telescope can't be put to good use without a finder of some kind. The reason is that even with its lowest-power, widest-field eyepiece in place, a telescope shows you such a tiny piece of sky that you can't tell exactly where you're aiming.
Three ways to take aim at the sky. Left: Lensless peep sights suffice for small telescopes with wide fields of view.
Buy Telescope Optics: A Comprehensive Manual for Amateur Astronomers on ekozamipypav.tk ✓ FREE SHIPPING on qualified orders. This is a 'comprehensive manual for amateur astronomers'. It describes the optical performance of most of the types of telescope bought (or built) and used by.
Center: Reflex sights project a dim red dot or circle on the sky, improving precision. Right: Finderscopes make more targets visible and enable the most precise pointing. But watch out for tiny, cheap ones with dim, fuzzy views.
A finder solves this problem. Three types, shown here, are commonly available. A few low-power, wide-field scopes come with simple peep sights; no optics involved. The next step up is the so-called "reflex" sight. This projects a glowing red dot or red circle on your naked-eye view of the sky; to set your telescope on a desired star or planet, you put the red marker on it. But you still have to be able to see your target with the naked eye. Most telescopes are sold with a real finderscope: an actual little telescope that rides piggyback on the main scope.
The finderscope's eyepiece has crosshairs that you set on your desired target. A good finderscope has several advantages. It brightens and magnifies the view, allowing you to find things beyond the naked-eye limit. When properly aligned, a finderscope also allows you to point a telescope more precisely than do peep sights or reflex finders. This is especially important whenever you're aiming at a blank point in the sky where your charts tell you an interesting, faint object ought to be.
On the downside, most finderscopes turn the view upside down, and many entry-level finders cannot be used by eyeglass wearers.
In fact, all too many consumer-grade telescopes come with cheap finderscopes that are so poor they're useless. Beware of any that has a tube hardly thicker than your finger, or that gives a dim, fuzzy view in the daytime. A poor finder is a critical weak point that can kill the usefulness of the entire scope. Once you warm up a new car and hit the road, you need a map to find your way — especially if you're in brand-new territory that you've never seen before! So it is with a telescope. In fact, even the most expert telescopic travelers use the biggest, best, most detailed sky maps they can get.
You may already own a planisphere, a rotating " star wheel " that helps identify constellations. Certainly you should be adept at using a wide-sky constellation map like this before embarking on telescopic astronomy. However, a planisphere alone will no more get you to the Cat's Eye Nebula, say, than a map of the Earth will get you to the shoe store at the corner of Park and Elm. To mine the heavens' riches, you need a set of more detailed star charts. Most astronomical atlases display all stars brighter than some specified magnitude, along with an assortment of nebulae, star clusters, and galaxies.
An atlas that reaches 6th magnitude the faintest you can see with the unaided eye under a dark, unpolluted sky suffices for users of binoculars. But an 8th-magnitude atlas like our famous Sky Atlas If you haven't used star charts before, there's no better way to get started than with binoculars see our primer on binocular astronomy.
Stargazing with binoculars offers two bonuses: views are right-side-up, and the field of view is wide enough to take in recognizable formations of naked-eye stars. The view in binoculars is very much like the view in a good finderscope. You might think that with computers in everything from dishwashers to cars, someone would be putting computers in telescopes by now. You're right!
Actually the computer doesn't go in the scope itself but in the mount, along with electric motors on both axes. A motorized telescope on a "smart" altazimuth mount can track celestial objects as accurately as one on a more bulky and complicated equatorial mount. Even better, once you set up the scope and initialize the computer with the current date, time, and location, it can if all goes well automatically point to thousands of celestial objects.
In the past, such futuristic capabilities would set you back thousands of dollars. But a new generation of battery-powered "smart" or "Go To" scopes has brought the commodity to affordable prices. A keypress or two gives the times of sunrise and sunset, moonrise and moonset, and the dates of meteor showers, solstices, equinoxes, and eclipses. Or choose a guided tour of the best celestial showpieces currently up, complete with a brief description of each on a digital readout.
These scopes can literally give you a beginner's course in astronomy. Still, these scopes aren't for everyone. For one thing, the affordable models have much smaller apertures than similarly priced entry-level scopes with no electronics. Second, a computerized scope can require a lot of careful setup that has to be done correctly at the start of each observing session in the dark! Third, these telescopes consume lots of electricity; some will exhaust a set of eight batteries in one night's use. Finally, when your "smart scope" fails to show a particular object, you may have trouble figuring out whether your eye or the scope's pointing is at fault — unless you already know the sky and your charts well enough to confirm that the instrument is indeed pointed to exactly the right spot.
Search for additional reviews and opinions on amateur astronomy Web sites and newsgroups. Then go ahead and call or write to makers of instruments you might be interested in.
Their brochures and catalogs should tell you much of what you want to know; if not, call and ask. However, nothing substitutes for firsthand experience.
Seller Inventory NEW Never used!. Seller Inventory P Brand New!. Seller Inventory VIB Book Description Willmann-bell. Condition: new. Seller Inventory think Ships with Tracking Number! Buy with confidence, excellent customer service!. Seller Inventory n. Harrie G. Rutten; Martin A. Rutten ; Martin A. Van Venrooij. Publisher: Willmann-Bell , This specific ISBN edition is currently not available. View all copies of this ISBN edition:. Synopsis Explains why there are so many different kinds of telescopes and what each type has to offer "synopsis" may belong to another edition of this title.