A response to this tweet: how to buy a telescope for children. (And beginners in general)

https://twitter.com/rnsoicher/status/1295171408281010176

If you find this helpful, do retweet.

First of all let me establish my bona fides quickly: I'm a public observatory volunteer at @GTCCASTRO. I've used telescopes ranging from beginner scopes to advanced amateur scopes to the big 24" CDK. And I've had experience with children looking thru & using telescopes.

How to get a telescope for a child.
Step 1: avoid hobbykillers.

Hobbykillers are small telescopes, usually using lenses, which come on finicky tripods and wobbly mounts. The optics are usually truly awful, sometimes not even using achromatic (true-color) doublet lenses.

also known as "department store refractors," these hobbykillers are so named because they are so frustrating to use that they end up being used once or twice, then left in the attic or closet gathering dust. Even well-known manufacturers, like Celestron and Meade, produce these.

To avoid them, simple method is just avoid refractors on tripods.

Avoid any telescope that advertises magnification instead of aperture size. These telescopes often come with tiny eyepieces and barlow lenses to magnify the image to far more than the objective lens can support.

Maximum useful magnification is about 50x per inch of aperture. So if you see a 2" telescope advertised as 400x MAGNIFICATION!!! you'll know this is a red flag.

Beautiful edited pictures of planets and especially nebulae on the box is another red flag.

Also make sure the eyepieces in the telescope are 1.25" barrel diameter. Older 0.965" eyepieces are usually trash--tiny fields of view, simple distorted optical layouts.

The important thing in a telescope is aperture diameter. That determines the brightness of the image, the resolution, and the maximum useful magnification. After that, the focal length is moderately important, as both it and the focal length of eyepieces determines magnification

Magnification = Focal Length of Telescope / focal length of eyepiece

So a 20mm eyepiece (standard in many beginner scopes) will give you 15x in a f=300mm telescope and 50x in an f=1000mm scope.

Is your kid ready for a telescope? <6yo not really interested usually. <8-10yo often can't use a telescope on their own.

A telescope is not an exciting toy, and it requires patience. Not every kid has that. Most objects gray blurs.But when it pays off, it can be really awesome.

Telescope or binoculars? Telescopes are better for kids since they don't require steady hands and don't need to be as lightweight. An adult can carry 2 lbs binos and get maybe a 50 or 60mm objective. A kid might be able to carry only a 30 or 40mm 1lb binocular.

binoculars for astronomical use are a good beginner tool, but not so much for a child, because their attention span tends to be shorter and there's fewer "wow factor" objects visible in a pair of binoculars. And you need darker skies.

Weight: 8-16lbs. This is based on guidelines for children's backpacks: 0.15 x body weight.

Cost: <$300. Expensive telescopes fitting these guidelines do exist, but you're buying a toy, not a serious instrument. Start small. They can upgrade when they're older.

Ease of use: this is very important. The telescope and mount must not have any complicated clutches, locks, or knobs. No complex setup. But it must also be sturdy and stable enough that it will stay where you leave it and it won't wobble.

This RULES OUT EQUATORIAL MOUNTS. Even an adult may find it difficult to understand how they work without already having a good understanding of the motions of the sky, and even then they might find them finicky or frustrating to use.

The best mount is an altitude-azimuth (up down and all around) mount. This is found in forks of doom (bad), photo tripods (decent), dobsonians (great), and other more complicated solutions

Computerization is not really good for a beginner telescope. Go-To scopes requires an often complicated setup procedure which requires foreknowledge of the night sky anyway, and it takes away the fun of finding objects all by yourself. Plus it makes the scopes more expensive!

Anything worth seeing in a small telescope can be found manually pretty easily, and beginner telescopes with computers are invariably smaller than non-computerized scopes.

Push-To could work as it can identify objects as well as help you find them, but it's not necessary.

The verdict: you want a tabletop dobsonian. They are by far the best bang for your buck, because their mounts are simple, easy to use, sturdy, but very cheap. Thus, almost all the cost goes to the optics, so they tend to have large apertures compared to telescopes on tripods.

You do need a sturdy table, stool, or chair to place the telescope on. Ideally a three-legged surface, since it won't wobble.

There's a few good choices.

Most of these make good adult beginner scopes too! But if you can handle a full-sized dob of 6" or more, go for that.

To unlock the high magnifications of these scopes, aftermarket eyepieces or magnifying barlow lenses are usually necessary. But these can be bought later on as upgrades. Barlows: 2 or more elements are necessary. Eyepieces: 3 (kellner) or 4 (plossl) or more lens elements needed.

<100 dollars (toys): Celestron FirstScope, Cometron FirstScope and Orion FunScope are cheap, lightweight telescopes that are fun and easy to use, BUT they have spherical mirrors instead of parabolic. The default FirstScope has awful 2-element eyepieces (Huygens/Ramsden)

$100-$150: Orion SkyScanner 100 (or Zhumell Z100) is a small lightweight tabletop dob with a parabolic mirror. I love mine. Zhumell Z114 is a great deal when it can be found for about $150, but it's not always available that cheap.

$200: Orion StarBlast 4.5. The preferred telescope of library loaner telescope programs. It is the original telescope which the Z114 is a knockoff of. It is powerful enough to see detail in Jupiter and lots of nebulae, galaxies, and star clusters.

$200: AWB OneSky. Half the profits go to the AWB charity. A 5" telescope, but it is a little bit more complicated to use (it requires collimation/alignment more often than the StarBlast due to the flextube design). Better resolution and light gathering than the 4.5" scope.

Also you should budget for some other nice accessories:

-Red flashlight to preserve night vision.
-a starwheel/planisphere (I recommend The Night Sky 2-sided planisphere)
-a notebook to write logs and draw what you see.
-Books

Books useful for beginners (maybe a bit older than 10yo)
-Turn Left At Orion
-Nightwatch
or:
-Astronomy for Kids: How to Explore Outer Space with Binoculars, a Telescope, or Just Your Eyes!
-(still looking for good amateur astro books for kids)
-HA Rey's The Stars (out of print)