Eyepiece Turrets

[Waxing_Gibbous (Peter)]

I almost dropped my 19 Pan. last night while changing EPs and as I am terminally clumsy this is bound to happen again.
Turrets seem like good idea. Presumably there is a downside to them. Other than expense and weight, why would you NOT use one?
TIA,
Peter

[gbeal]

Good question, and given your sig, the only one that won't fit is the 27 Pan?
Only turret I have had was the Zeiss amici prism M44 for my Zeiss scopes. Lovely, expensive and heavy. But it negated the need for a finder (didn't/haven't got one anyway) as I loaded the H40mm as well as three other higher powered orthos and away I went. Why I sold it escapes me.
Gary

[Wavytone]

They're fine and frankly I don't know why they're so rare, quite useful IMHO. Maybe we should try to coerce one of the makers of CNC crayfords to make a batch. Something akin to the old Unitron Unihex, for 2" barrels and with a dielectric mirror would be pretty sweet.

The difficulty I suspect is these add really only useable on slower refractors, cassegrains SCT's and mak's - no good on newtonians.

[Waxing_Gibbous (Peter)]

Originally Posted by Wavytone

They're fine and frankly I don't know why they're so rare, quite useful IMHO. Maybe we should try to coerce one of the makers of CNC crayfords to make a batch. Something akin to the old Unitron Unihex, for 2" barrels and with a dielectric mirror would be pretty sweet.

The difficulty I suspect is these add really only useable on slower refractors, cassegrains SCT's and mak's - no good on newtonians.

Why only slower refractors ?

[GrahamL]

Because I'd still have to load/unload it with eyepieces.. and I'm sure there would be a way I could manage to drop the whole lot at once

[Wavytone]

Originally Posted by Waxing_Gibbous

Why only slower refractors ?

Because these things aren't compact - they consume a fair chunk of focal length. The other reason is that some - and the unihex is an example - use a prism instead of a mirror - the prism adds spherical aberration. In a slow f/15 refractor this didn't matter but in an f/7 or faster scope it's intolerable.

[Waxing_Gibbous (Peter)]

Originally Posted by Wavytone

Because these things aren't compact - they consume a fair chunk of focal length. The other reason is that some - and the unihex is an example - use a prism instead of a mirror - the prism adds spherical aberration. In a slow f/15 refractor this didn't matter but in an f/7 or faster scope it's intolerable.

Ah!
The two I've been looking at, Tak & Tec, use a mirror. It would be going in an f6.2 scope. Ok? Not?
Peter

[gbeal]

Peter,
let me throw in a bit of unqualified advice here (and more in response to the possibility of the wanted advert paying off).
The Zeiss turrets I have have have all been prisms. OK, in my case the Zeiss scopes have been f11 or so, but the same turrets are touted at the APQ line of scopes as well, and these are f6 - f8.
While not completely disagreeing with the Fringe Lunatic, I do recall the common feeling that the Zeiss stuff was all prism for a reason, that it worked better in the refractors they were producing at the time.
So, if someone offers up a used Zeiss turret, and it has a prism instead of a mirror, grab it. Don't throw it out simply because of the prism.
Gary

[Wavytone]

Yes I'd it is worth trying one with a prism. For casual observing the convenience will outweigh any compromise involved.

PS re the Unihex (I know someone with one) was set up for a bunch of 0.965" eyepieces and one threaded base that accepts a big Unitron 60mm Kellner. Modern eyepieces won't fit it.

[gbeal]

Good point, as the Zeiss ones will be set up for a combination of M44 screw in and .96" slide in. Find a Tak or TEC one instead.
Gary