A Refractor Telescope for Clear Images The Sky-Watcher 70/900 AZ-Go2 Refractor Telescope is a 102mm Achromatic Telescope with a short focal length of 900mm. This shorter tube compared to other telescopes of the same class allows for a wider field of view with standard eyepieces. It is also conveniently sized for packing away and storing when not in use or in transit. Refractor telescopes are known for their classic image quality, with images being generally sharper than those from other telescope designs. Plus, there is no secondary mirror shadow, making it suitable for terrestrial viewing when used with a 45° erecting image diagonal. The AZ-Go2 Mount - WiFi-controllable with iOS and Android and compatible with SynScan hand controller, allowing it for smooth tracking and alignment. Use Wifi to control the telescope wirelessly with your mobile device; smartphone or tablet.