Apochromatic refractors have somewhat of a cult following; they are considered the finest instrument to observe and photograph the skies. Due to increasing popularity and lower manufacturing costs, these once-expensive telescopes are now much more affordable.
The Razor-sharp, false colour-free "APO" optics are perfect for visual and photographic applications. Advanced anti-reflection coatings optimize light transmission through the glass, approaching 99.5% transmission. The optical tube is fully baffled and blackened to reduce stray, unfocused light to maximize contrast.
Sky-Watcher chose Schott optical glass for the crown element. Schott pioneered the scientific development of optical glass. Their optical glass specialists are dedicated and experienced. The high levels of quality of Schott optical glass is further enhanced by their stringent quality control procedures. In short, you want the best, right?
The second lens element is comprised of FPL-53 Extra-low Dispersion glass, an exotic blend containing Fluorite. When combined with the Crown element, higher resolution and contrast is achieved by virtually eliminating chromatic aberration, an effect caused by colors focusing to different points.
This model, and previous incarnations are popular not only as a first scope, but as a second scope for autoguiding. It provides more field of view than a Schmidt-Cassegrain, making it the perfect companion.
Note: Picture shows a right-angle finder. This model actually ships with a straight-through finder.