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Celestron Astromaster 76EQ Telescope Review

Celestron’s AstroMaster 76EQ is the smallest reflector in the AstroMaster lineup – and arguably the best. Unlike the other AstroMaster reflectors, the 76EQ has quality optics – making it the only reflector in the AstroMaster line to do so. However, it still suffers from some shortcomings. Read on to understand why you should or shouldn’t buy it.

Basic Features

  • Optical Design : Newtonian Reflector
  • Weight : 16lbs
  • Focal Length : 700mm / 27.56 in
  • Aperture : 76mm / 3 in
  • Focal Ratio : 9.2
  • Magnification of Included Eyepieces : 35x, 70x
  • Finderscope : StarPointer red dot
  • Highest Useful Magnification : 150x
  • Mount Type : CG-3 Equatorial

Accessories

  • 20mm eyepiece with built-in image erector
  • 10mm Kellner eyepiece

Overview

The Optical Tube Assembly

The AstroMaster 76 optical tube is a 76mm (3-inch) f/9.2 Newtonian with a spherical primary mirror. A spherical primary in a larger, faster telescope such as the 130mm f/5 AstroMaster 130 will cause significant lack of sharpness and definition and is thus unsuitable for an astronomical telescope, but a 76mm f/9 sphere deviates very slightly from a parabola.

A telescope mirror must be accurately parabolized to within ¼ of the wavelength of green light (approximate 550 nanometers or 0.55 microns – so ¼ wave is about 137 nanometers or 0.137 microns) to satisfy the Rayleigh criterion and produce a sharp image, although a mirror of ⅙-⅛ wave is ideal and will produce a noticeably sharper image. A spherical 3” f/9.2 mirror only deviates from parabolic by well under 1/10 wave thanks to the extremely weak curve. This is more than acceptable for even a scrutinizing observer – large mirrors of this accuracy can cost many thousands of dollars.

Celestron Astromaster 76EQ

The only drawback, optically, of the AstroMaster 76 is its diminutive size. By the time one accounts for light loss from the mirrors and the secondary mirror’s obstruction, the AstroMaster 76 performs no better than a 60mm refractor. I consider a 60mm refractor quite small, but because they don’t need collimation and tend to be offered at a lower price than the AstroMaster 76EQ I would probably take the refractor. However, the 76EQ does offer the advantages over a refractor of no chromatic aberration and a shorter focal length – the former giving it better planetary/lunar performance, all other things being equal, and the latter giving it a wider field of view and lower power with a given eyepiece.

The AstroMaster 76 has a decent red dot finder mounted to the front of the optical tube assembly, and a more than adequate 1.25” rack and pinion focuser which is at least partially metal – the knobs are also rubberized metal, which is a nice bonus that looks pretty and doesn’t dig into your fingers. Both the primary and secondary mirrors can be collimated – which is a feature that although required, somehow isn’t always available with cheap small Newtonians.

Mechanically, the one fault of the optical tube is that it has an extremely short dovetail bolted directly to the tube. There is thus no way to rotate the tube to a more comfortable position, nor balance it if you are using heavy eyepieces/accessories – though the latter is not much of a concern, seeing as an expensive, wide-field eyepiece would cost more than the telescope and be the equivalent of putting premium sauce with frozen seafood that you heated in the microwave. But the inability to rotate the tube is annoying and I thought I would point it out.

Eyepices

Like all other AstroMaster Newtonians the AstroMaster 76 comes with a cheap, narrow-field 20mm eyepiece. This eyepiece really provides too much power (35x) to be a “low-power” eyepiece for a 76mm telescope and also has a narrow, straw-like field of view. Furthermore, its useless erecting optics and cheap coatings absorb a lot of light and degrade the image quality.

The 10mm Kellner provided with the AstroMaster 76 is acceptable in quality, though not my favorite, considering the scope’s sub-$200 price point I’m willing to give it a pass.

Mount

The mount supplied with the AstroMaster 76EQ is referred to in some literature as the “CG-2” but it is identical to the mount supplied with the larger AstroMasters which Celestron terms the CG-3.

The CG-3 is overkill for the featherweight 76mm Newtonian optical tube but certainly does a great job. The scope is rock-solid and I have zero complaints about stability.

The CG-3 has flexible slow-motion cables – there is only one for the right ascension axis, however, and you’ll have to swap it from one side of the mount to the other depending on which half of the sky you’re viewing. The mount also is, of course, capable of taking other telescope optical tubes, but a different optical tube would likely cost more than the entire AstroMaster 76EQ unit.

The CG-3 can be motorized with Celestron’s Logic Drive for hands-free tracking. Forget astrophotography, though – any kind of camera will make the scope top-heavy and there’s no way to balance it, in addition to the fact that this is an f/10 scope on a relatively simple mount with an only partially metal focuser.

Astrophotography

Apart from simple phone shots, forget any kind of astrophotography with the AstroMaster 76EQ. The scope is too small in the aperture to do useful work with a CCD camera for planetary imaging (a CCD would also cost more than the entire telescope), and a DSLR will strain the focuser and mount as well as render the telescope unable to balance properly.

For a sub-$200 telescope, though, this is all to be expected.

Usage

The 76mm aperture of the AstroMaster 76EQ is only enough to show you the brightest deep-sky objects, but it will do a reasonably good job on the Moon and planets. With the AstroMaster 76EQ, expect to see:

  • Mercury’s phases, with effort and luck
  • Venus’ phases
  • Lots of detail on the Moon
  • One or two dark patches on Mars when it’s at opposition every two years
  • Jupiter’s moons, cloud belts and Great Red Spot
  • Saturn’s rings, its moon Titan, and maybe the Cassini Division and some banding on the planet itself with good seeing
  • Uranus and Neptune as turquoise and azure dots
  • The Orion Nebula, the Ring Nebula, M13, the Pleiades, and a couple dozen of the other brightest deep-sky objects
  • Many double stars

What's The Bottom Line?

So, all things considered, do I recommend the Celestron AstroMaster 76EQ? Yes and no. For the same price you could get a larger tabletop telescope, but the AstroMaster 76EQ is unrivaled in its price range in optical quality and is the only thing I’d recommend that comes on a tripod. You will need to factor in at least an additional $20 or so at least to obtain a decent low-power eyepiece – I recommend a 25mm or 32mm Plossl –  so do keep this in mind when shopping, especially if you’re on a tight budget.

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