There is no diffraction pattern interference caused by a diagonal mirror or secondary mirror being suspended in the optical path (central obstruction) as is the case with reflectors. The crater has massive walls and the basin is 14,000 feet deep. SKY-WATCHER EvoStar 120ED APO REFRACTOR: Serious Amateurs will Love the SW 120mm ED-APO Refractor. The Earth's Moon offers a treasure trove of fascinating detail to explore with your SW 120ED-APO EQ5 PRO. The views you will experience are so clear and sharp it might just feel like a veritable space-walk. All lenses are uniformly air-spaced in their cell housings. Why fluorite? SKY-WATCHER EvoStar 120ED APO REFRACTOR: Serious Amateurs will Love the SW 120mm ED-APO Refractor Sky-Watcher high-performance ED-APO refractors offer premium optical performance for the discriminating amateur astronomer. as a primary scope, and was very happy with it...I began with Jupiter, as I was doing much research, including sketches and drawings...The contrast, sharpness, and detail of equitorial belts,festoons, swirls etc. Included tube rings, two-speed focuser, ***** rail, case, dust cover.. awesome. North of Tycho appearing brightly in a basin is the famous Rupes Rect (the Straight Wall), an 800 foot mountain that is a "must see" for amateur astronomers. M4, M10 and many other globular clusters can be seen well with the SW 120ED-APO refractor. The optics produce a velvety-black background across which stars of myriad colors are cast. Read our 101 article or get in touch. North of Tycho, appearing brightly in a basin, is the famous Rupes Rect (the Straight Wall), an 800-foot mountain that is a must see for amateur astronomers. Sky-Watcher ED-APOs – the Ultimate Refractors. The telescope is supplied with a right-angle 9 x 50 mm viewfinder with bracket; a 2-inch dielectric diagonal; two 1.25-inch LE (Long Eye Relief) eyepieces (LE 20 mm and LE 5 mm); a 1.25-inch focuser adapter; tube ring attachment hardware for mounting to the Sky-Watcher EQ5PRO Mount (or other compatible mount), and a foam lined aluminum carry/storage case. The Sky-Watcher 120ED also benefits from the inclusion of Schott glass for the positive front Crown element in the objective. Sky-Watcher is a leader in the design and manufacturer of ED-APO systems. First, it has superior dispersion characteristics compared to pure silica-based glass. There is no diffraction pattern interference caused by a diagonal mirror or secondary mirror being suspended in the optical path (central obstruction) as is the case with reflectors. Olympus Mons, a volcanic crater 375-miles across and 16-miles high, is just one of the quests your capable SW120ED can tackle. The objective lens cell is light-baffled to reject stray, unfocused light. The reason it gets a four is the focuser does not rotate, the dew shield does not retract, and the case is flimsy. Globs looks good, galaxies in Leo, Jupiter, bodes galaxy, even the Ring Nebula in Lira, M13. I am not an expert, but I was under the wing of someone who is. Mars is a challenge for amateur astronomers, but your SW 120ED will show some very interesting detail. Sky-Watcher offers one of the most extensive lines of ED-APOCHROMATIC refractors in the world. It is very well built and solid. We will be glad to help. As an astrograph, the Sky-Watcher Pro 120ED APO performs superbly, delivering crisp, high-fidelity imaging of solar phenomena (with proper filters) planetary, lunar and aperture appropriate deep-space phenomenon. If the scope cost $1000.00 more than I paid, it would be still worth every cent............ Sign up for OPT news, exclusive offers, and updates on the latest gear! I used it on a William Optics EZtouch mount (similar to aokswiss). These objects will stand out in bold relief contrasted against a very dark, velvet-black sky background. Nearby are Alphonsus, a 70 mile wide crater, and Ptolemaus, a prominent ancient crater 90 miles across with a heavily worn dark interior.