For those who want to enjoy outdoor activities in the garden,you deserve to have SV503 80ED telescope. SV503 80ED telescope's objective lens features an S FPL-51 extra-low dispersion glass ED element, which virtually eliminates chromatic aberration. This results in the great color correction for an ED doublet lens. A thoroughly though-out design and high-quality mechanical components. This very special SV503 telescope provides astrophotographers, visual observers or nature watchers with a unique source of pleasure when observing starry skies or nature watching. SV503 ED vs APO SV503 ED Doublet telescope only designed with one SPL-51 ED Glass and one Lanthanide glass. Both are very very good glasses. On the one hand, extra low-dispersion lens is used to increase light energy efficiency, and on the other hand, multi-layer coating technology is used to minimize the loss of light energy. In this way, SV503 Telescope will be as better as the normal quality APO, Even better than some general quality APO. 2" dual speed ack and pinion focuser. SV503 telescope has a nice and smooth focuser. Dual-speed ack and pinion focuser provides optimal focus control without backlash or image-shift.