I have attached a picture of the focuser on my Esprit 120ED. It seems to have extreme slippage, if it's not locked and you attach an eyepiece it will thunk down to full extension and you have to wind it back up.
With a lightweight camera it won't even wind up at all unless you support it with one hand.
I saw an article on how to tune the focuser that comes with a BD 120ED but it looks different and had Allen keys. Does anyone know how the adjustment works on one of these?
If it's anything like the 10:1 I have, the 4 screws may have "O" rings underneath the plate, on mine tightening what looks like the mounting screws also has an effect on the adjustment. The easiest way to find out how the focuser works is to just dismantle it; there's really nothing complicated about focusers.
Sounds like exactly what happened to my SW ED80. I didn't bother to try and fix it though so I'm not of much help... I did upgrade to a Moonlite though and if you can spare the money you won't regret it.
The grub screw located immediately below the lock probably increases the pressure to the underside of the drawtube. Other SW focusers have two grubs screws for this, so you might find that the two on either side of it do this.
As per Lee's comment, there really is only so far you can with adjusting these focusers and in the long term you would be so much better off swapping it out for a Moonlite or a Feathertouch. Since installing a Moonlite on my ED120 I would never, ever think of going back to a non-motorized focuser.
Thanks I'll pick up a hex key set and try it. I did manage to look up that patent number and there is a diagram of how it works inside. Hilariously it claims the design prevents the focus from changing when you lock focus... what a lie!
I looked at replacements but there aren't many for this scope, and the main one was close to $1k or more. Not worth it for a beginner like me, I just don't want it to lose grip so badly :-)
Thanks I'll pick up a hex key set and try it. I did manage to look up that patent number and there is a diagram of how it works inside. Hilariously it claims the design prevents the focus from changing when you lock focus... what a lie!
I looked at replacements but there aren't many for this scope, and the main one was close to $1k or more. Not worth it for a beginner like me, I just don't want it to lose grip so badly :-)
Repair/tuning of an SW focuser
