DESC: The ED S apochromatic refractor features Extra-Low Dispersion (ED) glass in its objective lens to suppress chromatic aberration to a virtually invisible level. Coupled with a medium f/7.7 focal ratio, the ED S series provide a sharp, color-free image of high contrast for both visual and photographic applications. The famous GP-E mount provides a lifetime of enjoyment as a reliable quality platform for visual and photographic use. This GP-E version is geared for those seeking a lightweight, portable mounting solution. The simplicity of the mount also makes it perfect for the beginner wishing to become familiar with equatorial mounts.