Aperture Is the Number That Actually Matters

Aperture — the diameter of the main mirror or lens — determines how much light a telescope can gather, which determines how faint and detailed an object you can see. Magnification, the number retailers print in huge letters on the box, is nearly meaningless on its own: any telescope can be pushed to absurd magnifications, but without enough aperture the image just gets larger and dimmer. Useful magnification tops out around 50x per inch of aperture; beyond that you’re viewing a blur.

For visual observing of the Moon and planets, 70–90mm of aperture is a reasonable start. For faint deep-sky objects — galaxies, nebulae, clusters — you’ll want 130mm or more, which is why Dobsonian-style reflectors are so popular with budget-conscious beginners: they deliver the most aperture per dollar of any design.

The Mount Matters as Much as the Optics

A great telescope tube on a shaky, mismatched mount is one of the most common reasons beginner telescopes end up unused in a closet. Read our full breakdown of alt-azimuth vs. equatorial mounts before you buy — the mount is often the actual point of failure for frustrated new owners, not the optics.