Sky watcher explorer 300pds 305mm 12 f1500 parabolic dual speed newtonian reflector optical tube assembly the new sky watcher explorer 300pds newtonian reflector incorporates the same superb mirror set as the explorer 300p but with two significant advantages a dual speed 101 ratio focuser is now included for excellent focusing precision also the tube length has been slightly shortened to optimise performance for prime focus photographyeven better performance for astro photography and vis