Sky-Watcher PRO 80ED APO Refractor: Portable Optical Powerhouse! Due to their unobstructed textbook-like diffraction patterns and exotic optical properties, the ED-APO produces the sharpest, highest quality imaging obtainable from any telescope optical design. These breathtakingly pristine celestial views are coveted by experienced amateur astronomers. Observing with SW PRO ED-APO 80mm Refractor Fortunate indeed is the amateur astronomer with a SW ED-APO 80mm refractor on a clear night with transparent skies and a stable atmosphere. The Sky-Watcher ED-APO 80mm is a modestly wide-field telescope offering bright, wide swaths of sky in a single view. It is well suited for wide-field astronomical observation of prominent nebulae, star clusters, and galaxies from a dark-sky location, or can be used as an astrograph for sky photography. As a terrestrial spotting scope or telephoto lens, the ED-APO’s performance is absolutely superb. Ultra high contrast allows the subtlest of details to be easily scrutinized under conditions of good seeing. The petite silhouette of the SW ED-APO 80mm makes for an excellent compact, portable telescope that travels light and fits a small space. At about 50-power structural detail becomes apparent in our solar system’s gas giants like Saturn and Jupiter. The Moon also exhibits striking crater detail along the lunar terminator. As an astrograph, the SW PRO 80ED delivers superb performance imaging a wide spectrum of astronomical phenomenon. Refractors—the Ultimate Imaging Instruments In a given aperture size, refractors will always exhibit sharper images than other optical designs because the refractor concentrates more light into the central airy-disk and first diffraction rings. 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. Sky-Watcher ED-APOs—the Ultimate Refractors Sky-Watcher ED-APO refractors provide the finest images obtainable—bar none—in their design class. If you are on a quest for the ultimate in pristine, near textbook-perfect astronomical imaging, look no further! Sky-Watcher ED apochromatic refractors deliver dramatic coal-back skies and faithful, contrast-rich views of planetary and deep-space phenomenon that are second to none. Sky-Watcher ED-APO refractors are the logical choice as an investment in advanced instrumentation for exceptional viewing or photography. Virtually Eliminates Residual Chromatic Aberration The Sky-Watcher ED-APO design assures virtual elimination of secondary, residual “false color" normally present in 2-element achromatic lens designs using Crown and Flint glass. Sky-Watcher APO refractors utilize a second lens element made from the mineral fluorite instead of Flint glass. Fluorite, CaF2, is a halide with unique properties and a hardness of only four. It is an exotic and difficult material to fabricate into a lens. Hence the cost of manufacturing a fluorite lens is quite high compared to a Flint lens element, for instance. Why fluorite? Fluorite’s molecular properties have several distinct advantages. First, it has superior dispersion characteristics compared to pure silica-based glass. It functions as a high-index lens with very low dispersion. We use the term ED to signify “Extra-low Dispersion". Fluorite also corrects well for spherical aberration. Schott Glass Used for Front Crown Element and ED 2 Lens Element The P80ED will benefit from the inclusion of Schott glass being used for the positive front Crown element i