[UniPol]

I bought a Bintel Crayford type focuser last week which is currently on special and took a punt that it would be a close fit to upgrade my vintage 4"/f15 refractor focuser. The stepped flange as supplied is 112mm O.D. and I machined it down to 108mm to suit the tube's I.D. and drilled the five mounting holes which also suited the holes already in the tube. The beauty of this upgrade is that the old focuser can be refitted as no modification was done to the tube.

With the focuser duly fitted and tested last night it performed flawlessly. Every eyepiece I tried came to focus within the 75mm focuser range. The 13mm Ethos in combination with the 2" diagonal came to focus at the 50mm mark. The focuser is super smooth and certainly can hold a load. I tried my Meade 30mm UWA Series 5000 which is larger and heavier than the Televue Nagler 31mm grenade and it lifted it up from a near vertical position with ease.

The new focuser in combination with the 1.25"/2" modern eyepieces has breathed life into my old scope. The views through this scope come close to my Tak TOA-130, showing almost no colour and pinpoint stars with perfect diffraction rings. Jupiter looked stunning with the 13mm Ethos which equated to around 115X. An added benefit of long focal length scopes is their smaller exit pupil at the eyepiece which means I don't have to wear my glasses. Most eyepieces exhibit greater clarity towards the edge of the field than faster scopes.

Cheers everybody, hope this little article has been of interest.

Steve B