The right telescope might be the spark for a lifelong appreciation of the night sky, maybe even the inspiration for a career in STEM. The wrong telescope can just as likely extinguish that spark. Here are a few things to consider before buying that special gift for your budding astronomer this holiday season.
Perhaps the most pervasive misconception about telescopes is the importance of magnification, or power. Many people are surprised to learn that telescopes don’t really magnify at all – magnification is accomplished by an eyepiece and is therefore variable – changed with every change of the eyepiece. Any telescope can achieve almost any magnification, which is why some “toy” telescopes are advertised as being capable of outrageously high magnifications to attract the uninformed buyer. They are not lying; a 60mm (2-inch) telescope can indeed achieve 750x just like the box says. What is not made clear is that the laws of physics limit the maximum “useable” magnification of an optical system. That 60mm telescope is at its best at about 20x — 40x and is rendered pretty much useless at anything over 100x. The image just gets too big to be discernable because there just isn’t enough light to work with.
What does a telescope do if it doesn’t magnify? It simply collects more light than your eye alone can collect. That’s because the opening in the telescope, called the aperture, is larger than the opening in your eye. The larger that aperture is, the greater the advantage in light gathering it has over your eye. The more light we collect, the more we can magnify it, but even for the largest telescopes, low to medium power is the most useful and the most used. The extra light is best employed by enhancing detail rather than enlarging an object’s size.
What you should take away from this is that the larger the telescope’s aperture, the more you’ll see with it. But there are trade-offs: the larger the telescope gets, the more expensive and bulkier it gets. What you should conclude from that is that there is no such thing as a perfect telescope. Your goal, instead, is to select the best telescope for your situation.
Step one in the selection process is to look for the largest aperture telescope that you can afford, handle, transport, and store. That might sound almost easy until you discover the bewildering variety of choices available. There are reflectors that use mirrors to collect and focus light, refractors that use lenses, and scopes that use a combination of mirrors and lenses. Then too, there is a wide variety of mount types. There are equatorially mounted scopes that can track the movement of a star by moving in just one axis, altitude-azimuth mounted scopes that are easier to point but can’t easily track, and fork mounted scopes that can be configured either way. Telescope mounts also come in a variety of complexity from traditional scopes that have to be guided by the observer alone, to “push-to” scopes that have digital pointing aids to guide the observer to objects and fully “go-to” telescope mounts that find and track objects autonomously once they are aligned to the sky. They each have their advantages and disadvantages.
Making the choice that best fits your needs and budget will involve some thought and a good bit of research. You should certainly call on the expertise and experience of your local astronomy club; they can help you with answers to your questions and give you recommendations. You can email questions to email@example.com.
A good place to see what is available is the website of Orion Telescope (www.telescope.com) where you’ll find many of the existing choices arranged by price, age, and experience level, or try the “New to Astronomy” page at OPT (https://optcorp.com/). Another good option is to search the websites of Sky & Telescope or Astronomy magazine for advice on telescopes for beginners.
If your intent is to buy a telescope for a youngster, be sure it is going to be easy to set up and use, is on a stable mounting and provides a bright, wide field of view. The younger your observer is, the smaller and simpler the telescope should be. In my opinion, it is probably a mistake to try and start a youngster out with a sophisticated “go-to” telescope. They are wonderful for the ease at which objects can be located, but they involve a good bit of alignment that can be frustrating for a beginner. Choose a simple mount – equatorially mounted scopes are probably not the best choice for a child. Finally, when it’s time to buy, get your telescope from a dealer that specializes in them. They can answer your questions and offer advice.
TED FORTE is a member of the Huachuca Astronomy Club