How to Set Back focus William Optics Zenithstar 81 with field rotator and field flattener #astro
9:25
Easy - How to Install a 5 volt ZWO EAF on a Refractor (William Optics Z81/Z73/GT81)#howto #astro
21:19
Introducing the William Optics GT81iv Refractor Telescope
11:46
To flat or not to flat? Assembly and discussion about the WO Zenithstar 73 and its Field Flattener!
12:42
Extension Tubes – Everything You Need to Know!
7:03
William Optics Adjustable Flattener Yes!
6:43
Astrophotography: Setting Up My Image Train with Proper Back Focus
23:44
What is BACKFOCUS?? And how to deal with it? - Starting Astrophoto for Lazy People - Ep 8
6:55