Eyepiece adaptor diameter

[David J H]

Apologies if this a reallybasic question with an obvious answer, I’m using a Vixen SP102M, which came with some 0.965” eyepieces. Although these work reasonably well, I think some better eyepieces would probably unlock some of the telescope’s potential, and be a better use of money than replacing or motorising the Super Polaris mount. I’m a bit confused about what adaptor I need to get to fit standard 1.25” eyepieces, however.

The focussing tube barrel seems to have a diameter of approx. 42mm;

Untitled by Tantris88, on Flickr

An adaptor is screwed into this, which seems to have a diameter of 36.4mm;

Untitled by Tantris88, on Flickr

 

So, do I need something like this to fit a 1.25” diagonal and eyepieces;

https://www.firstlightoptics.com/adapters/baader_1.25-36.4_adptr_2408195.html

Apologies if this is a really basic question, but I was expecting the focussing barrel to be a standard 2" diameter, and it's nothing like that. I do have the original brochure for the SP102M, but it doesn't list specifications like the focussing barrel diameter and what the measurements of the various adaptors supplied are, so I want to be sure that I buy the right thing.

 

 

[SiriusB]

Looks like Vixen paint in background... Vixen scope? Sorry i don't know what SP102M is offhand.

The old Vixen focusers i've seen had a 36.4mm internal thread, to which either a 24.5 or 1.25" adapter with the male 36.4 thread could be screwed in.

If that's the case the item in the FLO link should do you nicely & probably better than an original Vixen one.

Is the black part internally threaded in 2nd photo? 

The  drawtube @ around 40mm in 1st pic isn't going to work, unless that was a very cheap rule your using.😉 ....Or you know a friendly machinist.

 

[David J H]

Hello - yes, it's a Vixen 4" refractor. There is an internal thread in the adaptor;

Untitled by Tantris88, on Flickr

I'm not sure if this a male or female thread though - how would I tell?

 

 

 

 

[pete_gamby]

That is a female thread (internal) - external threads are male. The Baader adaptor that you posted the link to is what you need. There used to be Vixen adaptor but it has been discontinued.

Cheers, Pete

[johninderby]

I used the Baader adapter along with a Baader  ultrashort 1.25” eyepiece adaptor on. a ScopeTech 80 that had the standard Vixen thread on the drawtube.

Edited September 15, 2020 by johninderby

[David J H]

Thanks for all the help - much appreciated. I've now ordered the Baader adaptor, together with a 1.25" prism diagonal, and a Baader zoom eyepiece. Hopefully these will arrive fairly soon, and we get some clear skies!

[SiriusB]

Glad you got sorted David.

[John]

Brings back memories of my old Vixen SP102M - supplied with .965 inch eyepieces and diagonal as standard (quite nice ones though) and I had to get a Vixen 1.25" adapter for the drawtube to "upgrade".

Back then I don't think I even realised that 2 inch eyepieces existed - the 1.25 inch ones seemed large compared with the dainty little .965's