Thinking of getting your very first telescope? It can be overwhelming when you first start searching because there are so many to choose from. It’s so easy to get caught up in the excitement of a new telescope that you might not stop to think about how practical it will be for your lifestyle. But if you arm yourself with a basic understanding of different telescope sizes, types, and mounts, it will be much easier to pick a telescope in your price range that you will get the most use out of.
Bigger is better, or is it?
The main specification you want to consider when choosing a telescope is its aperture—the diameter of its main mirror or lens. The larger the diameter, the more light the telescope collects, allowing you to see fainter objects and more detail on nearby, bright objects like the Moon. Telescopes that have 4 or 5 inch diameters are great for viewing solar system objects like the planets, our Moon, and Jupiter’s moons. Viewing Neptune and Uranus can be difficult with a scope this small but it’s not impossible. A telescope of this size is probably a good starting point for a complete beginner.
If you want to take your stargazing up a notch and see fainter, deep-sky objects like star clusters, galaxies and nebulae, you’ll need something larger than 4 or 5 inches. But before you go for the biggest telescope you can afford to be able to see more objects, you should consider how convenient it would be to use a big telescope regularly. Will you want to bother dragging it out into the backyard each time you want to use it? Will you be okay transporting it to your favorite dark area or to a stargazing event? Do you want it to be something small children can use?
A telescope’s aperture is more important than its magnification, even though magnification is a feature you might see advertised a lot. Magnification depends both on the focal length of the telescope and the eyepiece you’re using, so if you have different eye pieces, you can change the magnification of your telescope.
But the aperture determines how much detail you will be able to see even if you have a large magnification. Having a small telescope with a large magnification will only zoom in on a blurry image because your telescope can’t collect enough light to allow you to see any more detail. Atmospheric conditions can also limit the detail you see. Even with the clearest skies, our atmosphere causes detail to be lost, so magnification only goes so far. The upshot of this is that magnification isn’t everything! A magnification of more than 200x won’t have much benefit for a beginner telescope.
How to calculate magnification
You can calculate magnification on your own by dividing the focal length of the telescope by the focal length of the eye piece. Both numbers should be readily available from the manufacturer.
Another aspect of a telescope you need to consider is its mount. This is what keeps the telescope steady and allows you to smoothly turn it to view different parts of the sky. There are 2 main types of mounts: altitude-azimuth (also known as alt-az) and equatorial. An alt-az mount is just like a photographic tripod; it moves up and down (altitude) and left to right (azimuth). Equatorial mounts have 2 axes, with one being aligned with the rotational axis of the Earth. This allows you to easily move the telescope to track an object as it moves across the sky throughout the night.
Equatorial mounts are a bit less intuitive for beginners, so I recommend sticking to an alt-az mount. However, if you’re really interested in tracking objects as they move across the night sky then you may want to consider an equatorial mount. To set up an equatorial mount you need to point one of the axes to Polaris, also known as the North Star, when using it for the first time.
There are also telescopes with computerised mounts that allow you to choose the object you want to view from a database, and then the telescope automatically moves to that object. They are also called GoTo telescopes because you are telling the telescope “go to” a certain object. These make it easy to find objects of interest for a beginner and are good for areas with lots of light pollution where it might be difficult to find reference objects using a sky map. But if you really want to learn the night sky, a computerized mount telescope might not be the best place to start.
Types of telescopes
Refractors use lenses to focus the images on the eyepiece. Refractor telescopes with larger diameters can get expensive when you pass 4 or 5 inches. One benefit is that they require less maintenance than reflectors—you just need to keep the lenses clean and you’re good to go.
Reflector telescopes use mirrors to focus the image into the eye piece. Some maintenance is required because mirrors can get out of alignment, especially if the telescope is being moved around a lot. The tubes of reflector telescopes are open, so dust can get inside, requiring cleaning. Something else to consider is that the mirror surfaces need to be recoated with aluminum every 10 to 20 years.
Although reflectors require a bit more maintenance, mirrors are cheaper to make than lenses, so reflector telescopes are often a better value for your money. You can get a reflector telescope at the same price point as a refractor telescope, but with a bigger aperture.
This type of telescope uses a combination of lenses and mirrors to focus the image into the eyepiece. They tend to be a little more expensive but their design allows them to have more magnification in a more compact tube. These telescopes also offer a wider field of view for their size, making them ideal for viewing larger objects like galaxies. This means you can get a powerful telescope that is still portable. Cassegrain telescopes make great tabletop telescopes, which can be very kid-friendly.
You can attach a smartphone to most backyard telescopes using a simple adapter to hold your phone’s camera lens in front of the eyepiece. This works best for bright objects like the Moon or Jupiter and its moons. Newer Apple and Android phones even have night sky modes that can bring out colors of the brightest deep sky objects like the Orion Nebula!
With telescopes, you get what you pay for. Anything too cheap (less than $100) might be too frustrating to use and not give you much viewing satisfaction. The starting price range for a good quality beginner telescope is around $200 to $400 with the upper end being for the computerized mounts.
Bigger and more expensive telescopes will allow you to see fainter objects but remember that the smaller the telescope, the easier it will be to transport, use and store when it’s not in use. Smaller telescopes are usually cheaper too, so you don’t have to break the bank to get a good view of the cosmos!
If you’re hesitant to commit to a telescope or you’re not sure stargazing is a hobby you will stick to, you can start learning the sky with a pair of good binoculars. You’ll be able to see craters on the Moon, some bright star clusters, and even Jupiter’s brightest moons.