2 replies to this topic

[jd200]

My first telescope in about 1969 was this Unitron 75mm refractor (I think it was a model 140 - with an Alt-Az mount).  I have owned it now for over 50 years.  For many of those years it has been in disuse, but as I got back into the hobby around 2013, mainly with an imaging focus - at some point I pulled out the old Unitron, attached a camera to it - and tried imaging the moon and sun.  It does a remarkably good job with very sharp images and the 1200mm focal lenght is great for those targets.

 

The only issue for imaging is the very basic and stiff rack and pinion focuser which requires me to do focusing manually - which is obviously very difficult.  I'm trying to look for some sort of after-market, preferably crayford 2 speed focuser that I might adapt to the Unitron scope.  The tube is 78mm ID and I'm having a really hard time finding anything that I can clearly see might be adaptable to that tube.  

 

So I was wondering if there were any classic scope owners in this forum that might have some advice for how to crack this nut.  I'm willing to get someone like Precision Parts to fabricate a custom adapter if I can figure out how to specify it.

 

Please help me out to get this classic old beauty to be productive in this new age of digital imaging.

 

Thanks!

John D.

[starman876]

check with the people that make the feather touch focusers.  They have all kinds of adapter.  However, the focuser might cost more than the  scope is worth

[RichA]

My first telescope in about 1969 was this Unitron 75mm refractor (I think it was a model 140 - with an Alt-Az mount).  I have owned it now for over 50 years.  For many of those years it has been in disuse, but as I got back into the hobby around 2013, mainly with an imaging focus - at some point I pulled out the old Unitron, attached a camera to it - and tried imaging the moon and sun.  It does a remarkably good job with very sharp images and the 1200mm focal lenght is great for those targets.

 

The only issue for imaging is the very basic and stiff rack and pinion focuser which requires me to do focusing manually - which is obviously very difficult.  I'm trying to look for some sort of after-market, preferably crayford 2 speed focuser that I might adapt to the Unitron scope.  The tube is 78mm ID and I'm having a really hard time finding anything that I can clearly see might be adaptable to that tube.  

 

So I was wondering if there were any classic scope owners in this forum that might have some advice for how to crack this nut.  I'm willing to get someone like Precision Parts to fabricate a custom adapter if I can figure out how to specify it.

 

Please help me out to get this classic old beauty to be productive in this new age of digital imaging.

 

Thanks!

John D.

You can buy focusers  2 speed ranging in price from $125 on up.  Problems are, most are made with threaded backs to fit specific scopes and Crayfords have short focusing lengths, which for a 3 inch f15 refractor can be a problem, so a long extension tube may be needed.  Using a GSO unit with an SCT connection might be the easiest way.  The GSO is narrow, has a reasonable draw and the SCT connection rotates.  All you need is to have a backplate made with an SCT thread size.

 

 https://agenaastro.c...dual-speed.html

Edited by RichA, 01 September 2024 - 04:40 PM.