Shortly after purchasing the William Optics GT81 FD, the focuser started to slip when used with a camera or heavy eyepieces. Adjusting the tension fixed that problem at first, but over time it became worse. Time to start looking for a replacement focuser! I had upgraded my FLT98 with a FeatherTouch focuser a year ago, so the most obvious choice would be to contact Starlight Instruments to find out if an adapter was available for the GT81. Indeed, they had one that was compatible; Wayne informed me that the adapter for GSO/AT RC telescopes is the same thread as the GT81. So what focuser to get? I chose the new lightweight focuser FTF2020 BCR-LW and added a 3.75″ riser. The FTF2020 focuser has a shorter drawtube compared to the stock focuser and the body is shorter as well, so you need a riser to be able to reach focus. With the 3.75″ riser, a TV reducer and Canon EOS will reach focus. A 2″ mirror and eyepiece will reach focus as well. For prime focus photography you need to extend even more. Total weight of the GT81 with the 3.75″ riser and FTF2020 BCR-LW is only 2.2kg (4.85lbs)!
