Sky-Watcher MC 127 Astronomical Telescope Review

Back in 1930 the astronomer  Bernard Schmidt (1879-1935), understood that it was possible to improve reflecting telescopes by using, in the center of curvature of the main mirror, an aspherical lens capable of eliminating the spherical aberration of the main mirror by introducing one of opposite sign. Thus was born the reflecting telescope. Schmidt, which, although representing an excellent compromise between compactness and photographic performance, presented the delicate problem of processing the aspherical plate.

In the 1940s the Russian  DD Maksutov and distinctly Dutch Bouwers and ours  Colacevich of the Arcetri Observatory, they understood that it was possible to replace the aspherical surface with a lens that acted as a concave meniscus concentric to the mirror which, if well designed, would be not only achromatic but also capable of introducing a spherical aberration capable of cancelling that induced by the mirror. Through this new optical design it was possible to achieve the same results as the aspherical lens of Schmidt but with a simpler procedure and with better compactness, since it was also possible to place the meniscus closer to the focus, in contrast to what was allowed by Mr. Bernard's scheme.
Thus the system was born Maksutov. Later, in 1957, John Gregory, replaced the convex secondary mirror by illuminating the central part of the meniscus, giving rise to the Maksutov-Cassegrain system also known as Maksutov-Gregory, a scheme which is still current today and used by almost all manufacturing companies, except the American one Questar, which prefers to illuminate the external part of the concealer.

This review will focus on a Maksutov Cassegrain with a diameter of 127 mm and a focal length of 1500 mm: the Skywatcher 127 MC.

FIRST IMPRESSIONS
A first visual analysis revealed how the build quality of Chinese products has improved: the optical tube, almost entirely free of plastic parts, is well-painted. The focus, which is operated via a knob similar to those of the new Schmidt-Cassegrain series, is Celestron It uses the movement of the primary mirror, the 31.8 mm diameter eyepiece holder is equipped with two screws for locking the eyepieces and the now ubiquitous connection T2 (M42x0.75) for astrophotography. The 6x30 mm finder scope has a very long slide of 10 centimeters that prevents the observer's face from coming into contact with the optical tube when searching for celestial objects. For alignment with the telescope, there are the classic three screws, the smallest of which has a spring-loaded return screw that allows the finder scope to be quickly moved for rapid collimation.
The primary mirror of the “SW 127” It can be aligned using three pairs of screws that allow the mirror to be tilted. However, the tilt of the corrector meniscus cannot be adjusted, as it has a pleasant emerald-green hue due to the anti-reflective coating.
The central obstruction is approximately 29% of the lens diameter, unfortunately amplified to 32% by the size of the lens hood. The interior of the black anodized body is smooth, while the primary lens hood has a fine array of diaphragms.

STAR TEST

The aberrations present in a telescope should not be considered mere instrumental defects but rather intrinsic factors The aberrations are also affected by all those alterations resulting from the assembly of the optics, the materials used for glass and mirrors, the accuracy of the workmanship, etc.

The star test It is therefore useful both to verify the degree of aberration containment achieved by the designers and the quality of the construction of the telescope as a whole.
On an evening marked by good seeing I analyzed the diffraction image provided by the “SW 127”,  of some of the brightest autumn stars.
There was a slight undercorrection and a marked strengthening of the first ring.
No optical stress was observed, but there was a slight difference in intensity in the diffraction rings, presumably due to some zonal errors that occurred during optical processing. After all, we're still talking about an inexpensive instrument.
One thing that pleasantly surprised me, especially when comparing it SW 127 to a Meade ETX used as a comparison, it was the minimum focus shift, a symptom of a better design of the mirror translation system, at least in the specimen at my disposal. This defect, however, appeared in a slight way when, during the star hopping, I moved the optical tube quickly toward the zenith and then focused. Re-collimating the primary improved the situation but it wasn't completely resolved.

EQ3.2 equatorial mount

Before analyzing the optical performance of the instrument, I would like to spend a few words on the equatorial mount that comes with it.
This is the heir of the classic EQ3, evolution of the Vixen New Polaris. The innovations are evident not only in the improved care of the components, but also in the new anodized dark grey tripod, extendable for over a metre, in the counterweight bar equipped with a sliding weight kit and in the possibility of using the motors in both right ascension and declination. The RA and declination axis blocks are undersized compared to a Vixen Great Polaris, but efficient for instruments with a weight similar to that of the SW 127. The mount comes standard with a decent polar finder scope that allows for quick setup of the instrument. The mount is also compatible with the Vixen Super and New Polaris mounts, while the bar connecting the Maksutov Cassegrain to the mount has threaded holes in the same position as the aforementioned mounts, making it completely compatible.
I was unable to verify the mount's tracking accuracy since the telescope provided for testing was not motorized. Vibration damping at 200x magnification with the 150mm optical tube was approximately three seconds, although this value depends greatly on the flexibility and consistency of the support surface. However, it seems to me to be a good result, comparable to equatorial mounts with similar characteristics.

Observation of the Moon and Planets

During the first week of November, I pointed the optics at the lunar surface and, with the supplied eyepieces, verified the good containment of stray light and the good contrast provided by the Sky Watcher Maksutov Cassegrain.
I was pleasantly surprised by the visual performance provided in this kind of observation, better than what I had abstractedly considered based on the mere purchase price.
On November 5, 2003, thanks to good seeing, I observed the central mountains, 1200 meters high, of the crater Gassendi, some hilly structures and two micro-craters; the rime that intersect its plateau but they were invisible. The rhyme, however, was very clear. Mersenius.
Inside the crater Clavius, I then observed, in addition to the five main craters, also other structures that were not perceptible in the 100 mm diameter achromatic refractor used as a comparison.
Reflections and ghosting were present but not bothersome. This problem stems not only from insufficient opacification and diaphragm but also from the telescope-eyepiece assembly. In fact, testing it with excellent Abbe orthoscopics, I noticed a general improvement in detail and reduced reflections.
The two eyepieces Super Ploss The supplied accessories showed not only an evident lateral chromatic aberration but also a poor sharpness. However, for high resolution observations, it is advisable to use accessories of superior quality, capable of bringing out the real performance of the instrument. SW 127.
After a break of a couple of weeks due to poor weather conditions, on the evening of November 20th, I examined the moon in its fourth day of phase, noting with pleasure that this small Maksutov-Cassegrain, on nights with perfect seeing, is able to tolerate 300x magnification, although it does not reach the brightness offered by a 100mm diameter ED refractor. This allowed me to appreciate the projection of the shadows of the domes near the crater.  Gambart  and the crater rim dotted with micro-structures inside the crater Posidonius. I would define the image as sufficiently contrasted, nothing to do with that offered by an apochromatic refractor, but certainly excellent in relation to its purchase price.

The planet Saturn also revealed many details, including the Cassini division, the lower albedo of its atmosphere near the poles, and some features in the equatorial region. A now-distant Mars, however, offered me only vague details of what it bestowed on observers during its summer opposition.

During the cold November evenings, I noticed that the instrument requires an acclimation period of at least an hour to the outside temperature, a factor not directly proportional to the aperture of its objective but rather to the optical casing that houses it. Indeed, in these climatic conditions, when attempting to observe the moon and planets within minutes of setting up, the images were always unstable, similar to those obtained with much larger telescopes. I slightly reduced the acclimation period by positioning the optical tube towards the side of the eyepiece holder without the cap, thus allowing the warm air to escape more quickly.

Being able to use a telescope Newton from the same diameter I decided to compare the Sky Watcher in the observation of deep-sky objects.
While appreciating in SW 127, the point-like nature of the vision of star clusters, such as M 35 In Gemini and the double cluster of Perseus, I found the view of galaxies or open star clusters only fair, where the Newton has always provided me with brighter images.
The Maksutov Cassegrain, however, excelled in the vision of double stars where we split with great ease and at only one hundred magnifications the unbalanced companion of Rigel and the famous double Epsylon Lirae.
For this type of observation, seeing permitting, this small Maksutov-Cassegrain can even take advantage of the four hundredx magnification.

Ultimately, I recommend this little one Maksutov-Cassegrain  to neophytes who wish to admire the innumerable details of the lunar surface and the most characteristic features of the planets of the solar system and who, occasionally, do not disdain also admiring deep-sky objects.

Disclaimer. This review was published on April 16, 2002. Please note that the impressions of use are entirely personal and given by Astrotest testers in complete freedom, without any commercial obligation or relationship and based on proven experience in the use of these optical instruments. Astrotest does not sell telescopes. For this reason, pFor any information, updates and/or changes to prices, authorized sales points or other information in general, please contact the official distributor, Auriga Srl, directly by clicking on the banner.