> >I changed the grease on my XT8 focuser as suggested and do get a
> >smoother focus, although now I get noticable image shift i.e when I
> >draw out the focuser I notice that before it moves back that it
> >shifts slightly upwards. I think this has something to do with the
> >internal plastic strips. Is there anything I can do, or are there
> >better focusers that I can replace the existing one with.
> If your XT8 is the newer Synta made model (with the silver finish on
> the outside of the focuser draw tube), you can easily adjust this!
> Both above and below the focuser lock thumb screw you will see two
> small holes. There is a tiny metric set screw in each of them. The
> screws adjust the tension on the plastic glide that bears against
> the draw tube opposite of the rack and pinion. Using a 1.5mm Allen
> wrench tighten these screws a bit at a time till the image shift
> goes away. Make them too tight and the focusing action will get too
> Replacing the focuser is the best bet but may involve a bit of
> work. Properly lubricated and adjusted the stock focusers are
> pretty decent though.
> Clear Skies,
PL gives good advice here and make sure that you optimize those
2 "hidden" set screws. Most people seem happy after re-greasing and
Unfortunately, I was unable to tighten them enough to minimize the
image shift enough without making the focuser too tight so that
movement was difficult and even jumpy. I think this is most
exaggerated with the Synta models or if you have long eyepiece
combinations. But, only you can decide if you still have this problem
after you have tried the adjustments your self yourself.
Large Orion or FocusKnobs will help. You may even want to try a
geared fine focuser knob or helical fine-focus add-on. The trouble
with these is that you still have the inherently sloppy gear drive
and may not solve your problem to your satisfaction. They also may
eat up $$$ that could better be applied to your focuser replacement
in the first place.
There are many nice Crayford focusers available from Williams-Optics,
JMI, MoonLite, FeatherTouch, etc. than run $135 and up. Tom Hole's
site shows his WO installation. Moonlite seems to have the best
adapters for the Sysquests that will only require minor drilling at
the most. I show mine under "Matts XT10" photos described under post
For the price of a good eyepiece, I think the focuser mod is worth
it. I've never heard of anybody regretting it if you can afford it.