The SV48P 102mm f/6.5 Astronomical Telescope has outstanding optics, high-quality mechanical components. Fitted with achromatic glass for good edge-to-edge viewing, fully multi green coated lens maximize light transmission eliminating false color. The 2.5inch Double speed focuser, for smooth operation, great feel and precise adjustability. This is a good telescope provides for astrophotography visual observers or nature watchers. SV188P star diagonal dielectric coatings; super flat mirror with dielectric coatings to reduce reflected light loss; provide an over 99% reflective surface; good for astronomical viewing SV188P star diagonal 90 degree viewing angle; diagonal reflects the telescope's light path 90 degree to provide a more comfortable viewing angle; best for observing objects overhead.