I've been using - off & on - an AP 6" F/12 since it was obtained for Kopernik Observatory & Science Center - Vestal, NY by Don Yeier - from an estate sale, when the telescope was about a year old. It spent many years on different mounts - taken to Stellafane at least 3 times. Today it is in a dome on a Losmandy G-11 mount.
The original focuser (believe it was a Unitron part supplied to AP by Don Yeier at the time) was pretty primitive - 'pot metal' casting, plastic strip supporting the rack - it did not survive use by "the educators" observatory staff for very long - and the scope now has a Moonlite 3.5" focuser on it. It makes an excellent up-grade.
Inside a dome - or with little to no wind - a G-11 is 'enough' to hold the AP6 - for both visual and imaging - but expect some 'giggle' when focusing - nothing awful - but certainly a lot more than I'm use to with my 20" Dob. The OP is talking 'visual only' - for imaging, I'd put an electric focus motor or it.
Yes it is *long* -- we mostly use 2 people to get it on the mount - or shift it in the tube rings for balance with heavy things like DSLR/Barlow or bino-viewer. It was certainly 'interesting' taking it to Stellafane - but lots of folks liked the views.
At some point - early 2000's???? - a large ring of cork fell out of the lens and down the tube. RC said "don't use it - send the lens in quickly" - which we did. In relatively quick time (few weeks) it was returned, cleaned, lens elements re-installed in the cell, cork or whatever replaced.
I've read that TBack quote many times over the years and - I'll take it as his opinion - which I find difficult to confirm. For about 10 years a friend owned the 'other' AP (he moved to Hawaii - with the scope!!) - and I viewed thru them side-by-side on many a night, and didn't see any difference. But what do I know? I also looked at Mars at opposition thru a friend's Obsession 20 F/5 Dob on the same night with both refractors (plus a C-14 and C-11) and -- a week later I bought a used Obsession 20 off of A'mart!
Of the many objects and views I've had thru that 6" F/12 -- the most memorable was -- the Comet Shoemaker-Levy 9 hits on Jupiter - first night they were visible. We were reading reports from Europe of big black spots on the planet - but I was not totally 'in to it' - until I got the observatory's 20" F/8 RC Cass on Jupiter in still very bright twilight. A yell from outside at the same instant meant that the guys outside with the 6-inch F/12 saw 'them' too. I walked out and the 'Superplanetary' was certainly living up to its name that night! Another memorable observation: the last transit of Mercury - I have images somewhere.
Fast forward to May 2022 - it was just used for a 'live' webcast of the recent lunar eclipse - and some claim that over 250,000 viewed at least some of it.
<< I'm at the wrong PC to find pictures - maybe later >>
Bottom line: If the price was right (compared to modern scopes and with the possible need for a new focuser) and I could deal with a "telephone pole of a telescope" - I would buy one.
Edited by George N, 24 May 2022 - 05:11 PM.