So long as you know what you’re buying, there’s no such thing as a bad telescope. If you’re on a limited budget, then a cheap, light telescope may be just the thing for you, allowing you to explore the Moon’s surface and a few other bright objects.
If you’re planning to spend a bit more on a telescope, then you can start to overcome some of the problems associated with cheaper models. Even on a budget, you’ll want to avoid telescopes that have:
Plastic lenses: Plastic lenses are cheap, and so you sometimes find them in very small, cheap telescopes.Plastic lenses don’t give nearly as clear an image as glass lenses do.
Too-high magnifying powers: You may also find small, cheap telescopes advertising themselves by their magnifying power (for example, 100 x magnification!), but that number alone isn’t important. You want a good balance between light-gathering power and magnification, so a larger telescope with lower magnification is usually far more useful than a small telescope with high magnification.
Shaky mounts: In short, avoid them.
Poor build quality: You’ll also want to check the whole telescope for build quality. If any part of your telescope is very low quality, then you’ll end up getting frustrated with it when it doesn’t perform as you’d expect it to.
