The Sky-Watcher BK250PDS OTAW-dual speed Newtonian Reflector incorporates the same superb mirror-set as the Sky-Watcher Black Diamond 250/1200 OTAW Series, but with two significant advantages. A Dual-Speed 10:1 ratio focuser is now included for excellent focusing precision. Also, the tube length has been slightly shortened to optimize performance for prime-focus photography. Even better performance for astrophotography and visual use can be achieved when used in combination with Sky-Watcher