A New Look at a Classic: Celestron C8 XLT Schmidt-Cassegrain

Credit: Celestron

The good: Versatile, light, fine optics

The bad: Needs cool-down time and near-perfect collimation


Over the past five decades, the Celestron C8 has established its reputation as a versatile, affordable, and  high-quality astronomical telescope. Available in myriad configurations ranging from bare tube assembly to wi-fi computerized, the C8 delivers the rare combination of competence in a variety of visual and photo/CCD applications. Here, we review the Celestron C8 XLT Schmidt-Cassegrain.

The 203mm aperture, f/10, SCT weighs less than 13 pounds (6 kg), and it can be accommodated by many medium-duty alt-azimuth and equatorial mounts, some of which will permit “grab-and-go” capability.

Critics of the Schmidt-Cass design tend to downgrade the C8 for producing “soft” images. However, a well-collimated and properly cooled example delivers very fine images, with absolutely no false color and excellent contrast on both planetary and deep-sky objects.

While there is some variability in the quality of individual scopes, most of the recent models are more than acceptable. When compared to a top-of-the-line 5-inch apochromatic refractor, the C8 shows about the same degree of lunar detail with stark contrast and a very bright image even at powers 200 and above. The chains of tiny craterlets near Copernicus, Rima Birt, and Triesnecker rills are strikingly apparent, and the lunar south is flooded with intricate crater detail.

Jupiter shows a wealth of belt and zone detail with the C8. Coloration of the north equatorial belt (NEB) is easily seen, and the Great Red Spot is impressive at 155x. The Galilean satellites can be recognized by their individual sizes and colors when the magnification is boosted to 275x.

Saturn is bright enough at higher powers to present a memorable view. The Cassini Division stands out with clarity, and belt detail on the planet is nicely visible. Overall, the SCT renders a brighter image than the 5-inch APO, but the refractor’s contrast and “etched” image quality can’t be equaled.

Close, difficult double stars such as Delta Cygni, Zeta Aquarii, and Antares are nicely resolved at 200x and above, and the scope meets the theoretical criteria for resolution.

The C8 is an excellent deep-sky instrument. The StarBright XLT coatings and effective baffling provide good light throughput, and a dark sky background.  The telescope resolves brighter globular clusters such as M13, M22, and M92 to the core, and the Orion Nebula shows its green tint and a great deal of fine structure. Only very large objects such as the Pleiades won’t fit, but an optional f/6.3 focal reducer can expand the field-of-view.

The C8 may well be the telescope of choice for observers restricted to just one instrument.

Read Larry Carlino’s complete review of the Celestron C8 XLT: Astromart


About Larry Carlino

Larry Carlino is an avid, life-long astronomy enthusiast, lunar, planetary, and deep-sky observer and the owner of more than 100 telescopes over the past several decades. He is a writer, a poet (latest work "Between") and a retired teacher of English.

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