Sky-Watcher Explorer-200PDS 200mm (8"") f/1000 Parabolic Dual-Speed Newtonian Reflector Optical Tube assembly. The new Sky-Watcher EXPLORER-200PDS Newtonian Reflector incorporates the same superb mirror-set as the Explorer-200P Black Diamond 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 optimise performance for prime-focus photography.Even better performance for astro-photography and visual use can be achieved when used in combination with Sky-Watcher's Newtonian coma corrector (Product Code 20233)*Note: the Explorer-200PDS has a larger 58mm secondary mirror, for enhanced field illumination, compared to the Explorer-200P which has a 52mm secondary. Please note this is an Optical Tube Assembly only, mount and tripod are available separately.