What telescope should you buy?

An eight-inch telescope will reveal this globular cluster in all its glory.

It’s the question I get most often. But neither public radio call-in shows nor running into you in the supermarket offers a place where I can impart what you need to know. And I deliberately didn’t offer this before Christmas, because you mustn’t hurry this.

Especially since you start off with wrong ideas. You think you can get a decent beginner’s scope for a few hundred dollars, right? And that you can quickly get the hang of using it. And that the sky brims with amazing sights if only you knew where to point it. Right?

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Reality check: Over the 49 years I’ve lived under our lovely planetarium skies, and have tried to help area residents and readers who’ve wanted a telescope, I’ve found one recurring theme: Purchasers use the thing once or twice and then never again. 

Will this be you, too?

These days, a popular choice is the “go-to” telescope. The ads say it’s computerized, with a database of 44,000 celestial objects. You select a target on the hand controller and the telescope automatically points there. Sounds wonderful. 

Except the thing won’t work until you’ve performed a series of set-up steps each time you take it outside. Requires around a half-hour. The job involves locating three stars and pointing the scope to each in turn and then hitting buttons in sequence, and a few other buttons, too. Will you do that? A half-hour set-up each time you’re in the mood to use the instrument?

That’s your first decision. If that works for you, then for under $1000 you can get a good “go-to” model like the Celestron Nextstar 5SE, recommended by The New York Times’ Wirecutter service. But now comes consideration number two. Which, actually, astronomers regard as number one. It’s called aperture.

That’s the size of the main lens or mirror. The bigger it is, the more you’ll see. Now, the moon and Saturn will look just fine in the five-inch-diameter NextStar. But if you jump up to an eight-inch telescope, everything gets clearer and brighter.

With targets like star clusters and nebulae, the so-called “deep space objects,” aperture can be critical. Look at the gorgeous globular star cluster that accompanies this article. Those dots are all suns! An eight-inch telescope shows it just as the photo does. Quite an experience. But in a five-inch scope, no stars are visible. Not one! Instead, the whole thing looks like a big blurry blob, bright in the middle and dim around the edges. A nothing-burger.

So if you bought the five-inch go-to model you might soon crave a bigger aperture. True, the 8-inch instrument is heavier and bulkier to transport in your car’s back seat. But the views are superior. Is it worth spending more money?

Actually, here’s a surprise: An eight-inch Dobsonian or Newtonian telescope costs less than the five-inch Nextstar. You heard right. Cheaper and yet it delivers a better view. But – and with telescopes everything is always a compromise – the eight-inch “Dob” is bulkier and doesn’t have a motor to track the stars, and has no go-to capability at all. Instead, you have to aim the instrument at your desired target using the included red-dot sighting device. 

This will be no problem with the moon, which is a fabulous object in all phases except when it’s full. And you can soon learn how to find Jupiter and Saturn, too. But with all other celestial targets, you’ll have to learn where things are.

Are you willing to learn the sky? Then you’ll know where that wonderful globular cluster is located. You can do this through private lessons, through books, or by joining a local astronomy club – all of which are good ideas, anyway.

My recommendation is to get an eight-inch Dobsonian. Woodland Hills Telescopes in southern California (818-347-2270) will take the time to recommend Dobs, including those currently on sale. Or else get the five-inch Nextstar and expect a different kind of learning curve, one that involves pushing lots of buttons. Either way, know that you can’t just buy a ’scope and then start seeing all kinds of amazing objects right away, except for the moon.

Accept that you’ll spend something approaching $1000. After a year or so, you’ll know whether you or someone in your family has developed a serious passion for astronomy. Then you can always spend more. (To replace the equipment in one of my observatories, I’d have to cough up $30,000. My friend Matt spent double that for his 24-inch PlaneWave telescope and mount. The sky’s the limit when the universe truly beckons.)

But don’t go the other way. No $200 telescope is worth buying. Cheap stuff will curse you with a wiggly tripod or mount or with inferior narrow-field, hobby-killing optics.

Be aware that only a few celestial objects are truly breathtaking. Most involve the appreciation of subtle details. Even through my big instruments, galaxies look like colorless smudges, while planetary detail is unsharp most nights thanks to the prevailing atmospheric turbulence over the eastern half of the U.S. Don’t expect to get images resembling the photos in magazines. 

That said, I can nonetheless attest, even when using a low 70x magnification, the good old half-oon takes my breath away. After a half-century I still stare at it for a half-hour at a time, seeing new exquisite detail. It never grows old.