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Optical delusions
by Bob Berman
June 26, 2008 01:00 AM | 0 0 comments | 4 4 recommendations | email to a friend | print
Here in the country, the stars spread lavishly across the sky like a living planetarium. The unaided eye is fine for learning the stars; but how can you take space to the next level?

These days a huge array of equipment is on the market, promising the moon. You can spend one dollar or 10,000 - the sky's the limit. But before you open your wallet, here's what you must know:

Telescopes

Astronomy goes with telescopes like ham and Swiss. Catalogues offer everything from $75 scopes boasting 600x to chiropractor-provoking behemoths. The telescope story is not a simple one, and no single instrument offers everything. The best ones are too heavy to carry in and out to the yard easily. The lightest are often too flimsy for a steady image. The "go-to" models that seem simple on paper require setup steps that many beginners refuse to do. You simply can't have everything.

One thing's for sure: Magnification means nothing. Most celestial objects look best using a modest 50x to 120x. Higher power merely makes the image blurrier. Yet catalogues advertise instruments with 300x or even 600x, because they know most folks equate "high power" with "better telescope." Wrong; totally wrong. Therefore, ignore all claims about power or magnification. It means nothing, zero, nada.

What does matter is the diameter of the lens or mirror that gathers the light. Look through the wrong end of the telescope and you'll be face-to-face with the optics that count. It's this diameter or aperture that tells you the true worth of the telescope. This is usually expressed in inches. Everything else being equal, a ten-inch telescope is better than a six-inch telescope, which is better than a three-inch. In other words, note the thickness of the tube: the fatter, the better. The length of the tube is unimportant.

What you'll see

The truth? Only about a dozen objects appear spectacular through a backyard telescope. Everything else looks like colorless smudgy blurs: all galaxies and nearly all nebulae. Serious amateur astronomers love those faint smudges, their eyes trained to recognize subtle dark streaks as meaningful features. But most people won't be impressed. Few objects show color. And astro-photography, which can indeed bring out colors and hugely increased detail, takes patience and practice; it's an acquired skill that's not for everyone.

The telescope crowd-pleasers are the moon, Jupiter, Saturn, a few globular clusters (in telescopes six inches or larger), a few nebulae and a few double stars. That's it. And you have to be able to find these things in the first place.

Bottom line: Do not overspend on a first telescope. Try one that's under $500 and see if you develop a serious and continued interest in astronomy.

A six-inch-to-ten-inch reflector telescope with a motor drive makes a wonderful telescope. But be aware: These are big and gawky, and must be carried in and out for each use. Telescopes don't work through a window, nor on a wooden deck, which vibrates even if you can't feel it. Telescopes belong on a lawn.

Binoculars

One of the most undervalued tools, the unbeatable talent of binoculars to deliver a bright image, wide field and stereoscopic view makes it a better choice for some objects than, say, the Keck Telescope. Their magnifications are too low for planets, but they're fine for loose star clusters and for sweeping the Milky Way. Avoid models over 10x, because the image will shake too much. The very best are the expensive, image-stabilized models. In reality, any binoculars whose second number (as in 7x35) is 30 or higher, and whose magnification is seven to ten, can provide satisfying views of many celestial phenomena.

Visit space on the cheap

Very few major observatories ever let the public in at night. In our area, the Mid-Hudson Astronomy Association sets out telescopes once a month in Wilcox Park, off Route 199 east of the Taconic Parkway. Its next meeting is July 25; call (845) 255-4719. Another way to visit space is my own four-session astronomy explorations, held annually since 1975 at Woodstock's Overlook Observatory. This year it starts July 31; call (845) 679-0785.

Even in our modern age, people remain enraptured by the night sky. Optics provide some fascinating sights, but ultimately are unnecessary. After all, the ancient Arab desert-dwellers had nothing, yet knew the heavens so well that their star-names are the ones we still use today.

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