So Your Child Wants a Telescope

At some point, if they haven’t already, your child may have an instant interest in space and you’ll want to help them along with a telescope. As with all kid’s interests, it may be fleeting, or it may be more persistent. Buying the cheapest telescope you can find is sure to make it a very temporary experience. Telescopes and mounts range from $30 to more than most houses. The $30 scope will be a useless toy, and the higher end scope would most likely sit in a permanent observatory. You don’t have to spend thousands for an enjoyable experience, but you’re best off spending a few hundred dollars (US) to avoid a lot of pitfalls common with beginners.

Why you don’t want that $100 department store telescope?

The packaging and advertising of these scopes is attractive… 400x magnification… a huge image of Saturn with definition in the rings… deep views of lunar craters… don’t believe it! Even on the clearest night, 250x magnification with the best quality scope and eyepiece is pushing it.

The optics (quality of glass) in these refractor telescopes isn’t much better than a drinking glass, and tend to be about as durable. That said, you can get a view of the moon and planets with one of these scopes. They aren’t completely worthless, but they’re usually lined with plastic and fragile.

These department store telescopes are mass produced with little quality control. You’ll often find halos around brighter objects and/or extreme difficulty getting perfect focus due to poorly aligned elements of glass, or cheaply ground mirrors with inferior reflective coatings.

Any included eyepieces will be one step above looking through a plastic toy and will have a very narrow apparent field of view that is difficult to navigate. I would equate it to trying to look through a straw. I have some quality eyepieces (TeleVue Naglers) that are very forgiving and do even help along a cheap telescope, but they are $300 each!

Any included tripod will have cheap manual control knobs with plastic gears and the stability equivalent of a $15 camera tripod. At magnification, the slightest bump will send an object bouncing all over the field of view, if not out of it completely.

I won’t name any of these scopes, because I don’t want to bash any particular brand or type. As a guide, if it’s form Amazon, Walmart, or any other large retailer, and under $150, it will fall into this category. You may not want to spend the money up-front just to see if your child wants to expand their interest, but you’ll be setting yourself up for a failed attempt. Better telescopes have a higher resale value and you’ll can make up the difference if the interest fades and you decide to sell the telescope.

OK, So What Should You Get?

There isn’t one definitive answer to that question, but there are some things that will make this an easier experience for everyone involved.

A Refractor-style Telescope

A refractor uses two or more lenses to collect and magnify the light coming into the scope. They are easy to setup, durable and relatively maintenance free. This image looks way more complicated than it is. This really just shows how the light is collected and magnified. 1 is the big lens, or objective lens. 2 represents the second lens, which in a simple refractor is the eyepiece you’re using.

A Newtonian Reflector collects light at the back of the telescope on a big mirror called the primary mirror, and reflects it to a smaller mirror called a Secondary mirror. The image on the secondary mirror is what you’re focusing on.

Reflectors at this level are often less expensive, but there is a reason, and that reason is not quality. I currently use a Newtonian reflector for my imaging that was only $200 (for the tube). At the beginner level, a reflector can often produce better views than a refractor. However, reflectors are bulkier and need regular adjustment, called colimation. The two mirrors used in a Newtonian move with temperature changes and even just from setting up and taking down your equipment. Refractor glass elements are cemented in place and retain colimation from the factory.

A Motorized GoTo Mount

There are two main types of telescope mounts and the both are vailable with GoTo options.

The first is an ALT/AZ mount. The ALT/AZ is for Altitude (ALT) and Azimuth (AZ). All that means is up and down and side to side respectively. For visual observing objects, this is all you need. Most will look similar to this SkyWatcher model.

The second type is called a German Equatorial mount. This type sets a center point at the celestial pole, which is right next to the North Star, and then rotates around it. This is not required for visual use, but it is absolutely necessary for imaging the sky. The prices are of these mount are also quite a bit higher. These are much more complicated to use and I recommend against starting your child with this type of mount.

A motorized GoTo mount  is not a necessity, but I do recommend it for ease of use. After initial setup, a GoTo mount will point to an object in the sky for you with the push of a button. It will “GoTo” the object you select. While more expensive than a manual mount, a motorized mount removes a lot of the guess work and prior required knowledge of the sky. Some view this as cheating, but I’m all for using available technology to aide in learning. After hitting your target object, the mount will automatically track it across the sky for you.

If your child advances and wants to start taking images of objects, they will be able to take pictures of the moon, planets and star clusters using the ALT/AZ style mount since these all require short exposures. Deep space objects like nebulae and galaxies require several longer exposures and an Equatorial mount. An ALT/AZ mount will follow the object, but it does not rotate with the it. Remember, side to side and up and down only. The lack of rotation in the mount causes the object to rotate in your field of view. The EQ mount follows the movement by rotating around a center-point, matching the spin of the Earth and subsequent apparent rotation of the object.

A Sturdy Tripod

Vibrations, wind and accidental nudges can ruin an entire night. A solid tripod can go a long way in helping to avoid these pitfalls. Look for steel rather than aluminum. Aluminum makes for a light-weight and more portable option, but that weight saving comes with a significant loss in stability.

That sounds like a lot of dollar signs doesn’t it? It doesn’t have to be. And remember, a better quality setup will retain more of a resale value if it doesn’t work out.

You’ll see an aperture number in millimeters – that’s how big the objective lens or primary mirror is, and a focal ratio, or f-number on these. The bigger the objective lens or mirror, the more light collected. Without getting into the math, the f-number (f/5 in this first case below) has to do with how far apart the lenses or mirrors are. The farther apart they are, the higher the f-number. The closer together, the lower. A high f-number provides a higher magnification, but a narrower view and brightness. The lower f-number gives you a wider, brighter picture, but doesn’t offer the highest magnification. These are what I’d consider all-around telescopes. There are different types specific for planets or small galaxies, but at a beginner level there’s no need to get that specific. Here are a few options for quality beginner scopes.

Meade ETX 80 Observer:

This scope will give you fairly wide-field views at f/5 with an 80mm objective lens. It comes with two eyepieces, a built in barlow (additional magnification), and a backpack to carry it all around in. The wider view will limit your magnification a bit, but will also be more forgiving. You can usually find this for under $300. If I had to pick out a negative for this package, it would be the aluminum tripod. It’s so light that there is a hook included to add weights for stability.

Celestron NexStar 102 SLT:

The Celestron is more expensive at about $400, but offers 102mm of aperture and an f/6 focal ratio. What that means is that it collects more light, faster than the 80mm scope above. That’s a bit of an over-simplification, but collecting more light is the point of a larger telescope. This also comes with two eyepieces and sometimes you can find it with a barlow lens thrown in for free. The stability of the stainless steel tripod adds to the ease of use and value. The aperture increase and more stable tripod are two very important factors, and account for the higher price.

Celestron NexStar 130 SLT:

This one is an f/5 reflector option to the 102 SLT with the same mount. You can usually find the 130 SLT for a bit cheaper than the 102 SLT. At the time of writing this, the prices I see range from $350-$375 (US). The primary mirror is 130mm and offers about 40% more light gathering power than the 102mm refractor. Be aware, a reflector telescope will require frequent adjustments. Once you get the hang of making the adjustments, it’s fairly quick and easy, but it is something to keep in mind. This Sky and Telescope article, while very technical, still has a lot of information about how a Newtonian reflector works and can be adjusted.

Any of these scopes would be a good choice for beginner quality and ease of use. You don’t want your child’s first experiences viewing the sky to be frustrating and fruitless. Follow the directions included with the scope for setup and pointing accuracy. The initial setup and alignment will help you and your child enjoy more time viewing planets, the moon or galaxies rather than searching for them. This investment might be more than you were initially thinking of spending, but a telescope that is often used is worth exponentially more than the one that sits in a closet.

Clear Skies – KA