Interesting report Adrian.
Had to convert inches to millimetres…1.5" = 38mm. Went Metric while I was in 5th grade
It's interesting that the CC needs quite a bit of in focus like the ES Focal Extenders do, unlike traditional barlows.
Luckily my 10" Newt is set up for imaging, not that I will ever put a camera on it, so I have about 60-100mm in focus to play with. With the TV CC I have to add a 35mm extension tube to get focus, with a Feather Touch 2.5" focuser racked all the way out.
I ordered an ES CC which I hope will get here in a couple of days and can compare to my TV CC type I.
Lack of instructions??? Suppose you just make your own up. I going to have a guess and try it like the TV CC with par-focal rings on the eyepiece and start with the ES CC screwed all the way out. Start with the eyepiece with the longest out focus, ES 16 or 28mm 68º in the CC, and move the helical inwards until it shows pin point stars all the way across….
It's going to be a bit of mucking around. Sounds like these CC will be good in f4 scopes i.e. imaging scopes.
Hope to have the thing by the weekend.
Matt