Thursday, January 08, 2026

Experiment: Canon FD 300mm f2.8 with crayford focuser

I am selling this ancient self modified lens.

A sudden thought came to me, why not attach it directly to a crayford focuser?  It shouldn't be too difficult.

I have all the thread specifications, connecting adapters might not be too difficult to find.


I even removed the camera angle adjuster to test, but unfortunately, the focuser was a bit too long for infinity focus.

I believe that a short profile SCT focuser might work, and I actually have one.  Might try again later, I just treat it as a short break for me.

--

Equipment shuffling

A further thought comes.  I am trying to see if this CYCK could be attached to my Ranger tube so that the JMI NGF-CM could be released?

The answer is not simple.  

The Tele Vue Ranger has a 3" 24 TPI thread, while the CYCK has metric thread.

I should have fabricated a SCT adapter for my Ranger tube instead of custom made for the NGF-CM.  So it's very much irreplacable now.

I could go another route: attaching the ZWO focusing motor to the JMI NGF-CM?  I might work but then it's not easy to adapt the NGF-CM to another telescope since it has nothing but a groove like attachment.

If I could find a NGF-CM SCT adapter, the whole thing would become possible.  However, the JMI seem dead?  It's not easy to come back such an adapter.

No comments: