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ApertureBuy the right telescope, not the biggest one

One model, judged by its numbers

Celestron AstroMaster 70AZ

The shape most people picture when they picture a telescope. Sealed tube, nothing to collimate, and a standing eyepiece height that suits sharing.

Family · 70–90 mm refractor on an alt-az mount

What it shows, really

These circles are simulations, computed from the aperture, the magnification and the sky — indicative, not exact. A real night also depends on the turbulence, your eyes and your experience. Closer to the truth than the photo on the box; still not a promise.

Under a suburban sky (Bortle 6), through a common 25 mm eyepiece for wide targets and a 10 mm for planets. Every circle is the true field — nothing is enlarged.

The numbers

Aperture70 mm
Focal ratio900 mm · f/12.9
MountLightweight alt-az on an aluminium tripod
Typical weight4.5 kg
Eyepieces20 mm and 10 mm
Useful magnification12× to 140× at 70 mm
Resolution (Dawes)1.7″ — the tightest double star this aperture can split
Faintest star, suburban skyaround magnitude 10.5
Observed price175 seen 2026-08-17

Made for

  • Sharing it with children · 4 out of 5

    Standing height, sealed tube, and no mirror to knock out of line.

Not made for

  • Nebulae, clusters and galaxies, by eye · 2 out of 5

    Bright clusters and the Orion Nebula. Galaxies are mostly out of reach.

The family it belongs to: 70–90 mm refractor on an alt-az mount

What it does well

  • Point it and look. No collimation, ever
  • The eyepiece stays at a comfortable height wherever you aim
  • Doubles as a daytime spotting scope

What it costs you

  • 70–90 mm is not much light. Deep sky is a short list
  • Cheap achromats show a violet fringe on the Moon and bright planets
  • The bundled tripod is usually the weak part — a wobbly tripod ruins a good tube

Worth knowing about this model

Listed because it is what most high-street searches return. The optics are fine for the Moon; the tripod is light enough that the image shakes for several seconds after each touch. A tabletop Dobsonian at the same price gives roughly three times the light and a steadier view.

Everything about 70–90 mm refractor on an alt-az mount →

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Where to buy

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