Before you buy your first scope

If you’re first starting out in astronomy and you want a quick primer on how to select and the important factors, this is the place to start. We’ll go over the basics of telescopes and familiarize you with the lingo commonly used. There are a lot of excellent resources on the Internet and we will refer to them so you can learn more at your leisure.

The #1 piece of advice we can give is this. Don’t buy a telescope without looking through a few different types and talking to other astronomers.

We regularly have public star parties at Darling Hill Observatory (DHO) where members bring their scopes to the field and we have our own 16in reflector and an 11in Schmidt-Cassegrain (SCT) for use. Our members love to talk about their scopes and will let you look through the eye pieces and talk about what they like and don’t like about their equipment. Some of our members have decades of experience to share. If you’re a member, you’re welcome to use the observatory any time and on clear nights there will usually be someone ready for some star gazing. Of cource, there is also our mailing list where you can ask questions, our Facebook page, as well as the monthly meetings. In addition, we hold two scope clinics in the year to help new astronomers get familiar with their gear and to talk about astronomy.

There are a few top level things to consider in buying a new telescope besides costs like the types of objects you want to see, the size and weight you can reasonably handle, and how much electronics you want to include. There is no single scope that is best for all cases and any choices you make is a trade-off elsewhere. With unlimited funds, you can lessen some of those trade-offs, but for the rest of us, we compromise. Also, as you gain more experience, you will figure out what you want and don’t want. You can always add tools and aids later.

  • What do you want to see? This is the first and most important question. Scopes that excel at planetary objects like refractors will be OK with deep space objects (DSOs). Reflectors, especially the larger ones, excel at DSO’s and are OK with planetary objects. Catadioptrics (the stubby scopes) are OK at either but suffer more trade-offs. However, Cats are usually easier to use, smaller and lighter to carry, are motorized and computerized. Astrophotography scopes are a whole different set of things.
  • What can you lift? Telescopes can be both heavy and unwieldy to move around. Unless you have a permanent mount, you’re going to get your exercise. The scope that is hard to move is a scope that doesn’t get used. Better to trade off size and weight on a scope you will use regularly than get a scope that is too heavy to move easily. If you can, go to star parties early and see what others have to do to set-up and ask to move the parts.
  • How much electronics do you want? Scopes today range from fully manual to fully automated. A budding astronomer can know nothing of the night sky, buy a computerized GoTo scope and be viewing objects in a night at a reasonable–for telescope prices–cost. Computerized scopes come with a computer and an object database but they can also be connected to a laptop or tablet which offers more advanced features and usually larger data bases. The downside if electronics is they can be finicky and you need to have power on site or bring your own.

Regardless of what scope you end up with, lets set some expectations of what you can see. A moderately sized scope and even binoculars gives impressive views of the Moon. 1/2 Moons are best because the sun is at an angle and throws shadows that highlights surface features. Planets need a decent sized scope to support the needed magnification to see details. A 6in scope can show bands and the Great Red spot on Juniper, the rings of Saturn, including the Cassini division, and her moons. Mars can be a fickle sight. Venus is a white circle and shows phases while Mercury is hard to get because its so close to the Sun and closely follows its rising and setting. Neptune and Uranus, when are visible are colored dots and Pluto, the dwarf planet (Long live Pluto!) is a dim dot. Comets are often visible when they are near.

Deep Space Objects–the colorful nebulae and galaxies that grace coffee table books, magazines, and the Internet–are often indistinct gray smudges with little detail. Our eyes, even with telescopes, simply can’t collect enough light to reveal details. For that, you need Electronically Assisted Astronomy (EAA) which may help somewhat, or astrophotography, both of which collect more light streaming from lights years away for your viewing pleasure. Aegna Astroproducts has an extensive explainer on EAA. Attending star parties is a good way to see what is possible.

We’ve broken up this primer into sections to make it easier to read and we point to references for greater detail.


Mike Fratto is an amateur astronomer who can be found in his backyard or at Darling Hill Observatory on the rare nights its clear in Central New York.