Two main factors limit how much power you can use productively with a given instrument: aperture (again) and atmospheric conditions. When seeing a telescope for the first time, a novice often asks, "How much does it magnify?" The answer is, "Any amount you want." Any telescope can provide an almost infinite range of magnifications, depending on the eyepiece that you use with it.īut don't get the idea that super-high powers will do you much good. That means that a little 70-mm scope gathers 100 times as much light as your eyes, revealing amazing detail on the Moon and pleasing views of all the planets, as well as showing hundreds of star clusters, nebulae, and galaxies. That may not be a problem if you keep your scope stored in a shed and wheel it out for use, but a bulky telescope could be a show-stopper if you need to carry it up and down many flights of stairs, want to take it on an airplane, or store it in a cramped apartment.Īlthough it may be less capable, even the smallest telescope is a huge improvement over your unaided eyes, which have a measly 7 mm (0.28 inch) aperture at best. Telescopes with big lenses or mirrors tend to be heavy and bulky. That’s hardly surprising considering that the large aperture gathers nearly 13 time more light than one only 2.8 inches across.ĭoes that mean you should rush out and buy the biggest telescope that you can afford? Not necessarily. Let’s compare the extremes: Small objects such as planets appear much crisper and more detailed through a 10-inch scope, and faint objects such as galaxies and nebulae appear bolder. In general, the larger a telescope’s aperture, the more impressive any given object will look. Apertures commonly recommended for beginner telescopes range anywhere from 2.8 inches (70 mm) up to 10 inches.
A scope's aperture determines both its light-gathering ability (how bright the image appears) and its resolving power (how sharp the image appears). The most important aspect of any telescope is its aperture, the diameter of its main optical component, which can be either a lens or a mirror.
Aperture: A Telescope's Most Crucial Specification It’s often cheaper to buy one telescope that’s specialized for visual observing and a separate scope for astrophotography than to buy a single scope that is suitable for both jobs.īefore examining the different telescopes available, it's worth knowing the basics of how they work. If you’re new to astronomy, it’s smart to gain a thorough grounding in visual astronomy before you contemplate astrophotography. It’s easy to take snapshots of the Moon through any telescope, but long-exposure photos of galaxies and nebulae require lots of time, patience, and specialized equipment. This guide concentrates on visual observing, as opposed to astrophotography. What do you most want to look at? How dark is your sky? How experienced an observer are you? How much are you prepared to spend? Where will you store your telescope, and how much weight are you willing to carry? Answer these key questions, familiarize yourself with what's on the market, and you'll be well on your way to choosing a telescope that will satisfy you for many years to come. We'll also look at the tradeoffs, because every instrument has its advantages and disadvantages.īefore you buy anything, you must determine what's important to you. We'll start by exploring the basic features common to all telescopes, and then look at some specific designs. Whether you're seriously considering buying your first telescope or just daydreaming about it, this guide will help you narrow your options. Naturally, this brings the burden of choice: the bewildering variety makes it hard for an uninformed consumer to make the right decision on what type of telescope to buy. Never before have novice stargazers been presented with such a vast array of telescopes and accessories to pursue their hobby. This is an exciting time to become an amateur astronomer.
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