Good instructions! Thanks!
My original report was the one that included instructions regarding
getting the black thumbscrew tight. The tightening of this really
only affects one aspect of the focuser, which is to make sure it is
perfectly alligned with the main shaft, which helps keep it smooth.
Otherwise if it's not tight enough, it will slightly flex or warp the
main focuser knob shaft, which can cause it to sometimes exhibit a
smooth-rough-smooth pattern as it turns. It does vary from model to
model a bit as to what adjustments provide the perfect tensions and
smoothnesses so if you are willing to experiment a little, it is
likely that you can get things perfect if you are willing to.
Depending on the model there are three places that could cause
slipping, which have all been mentioned so I will summarize in case
it helps anyone.
1) The little allen head that tightens to the main shaft that turns
may be round or may be a half circle, but either way it should be
tight so that it doesn't accidently allow for slippage.
2) The little allen tension screw that adjusts the tension of the
actual focuser draw tube needs to be tight enough to prevent slipping
(note, that the focuser lock should always be loose when adjusting
the tension, or the two will fight with each other)
3) The small brass slotted tension ring on the inside of the two-
speed focuser adjusts the tension of ONLY the two speed part of the
foucser relative to the main focuser.
Through a series of steps, trial and error will allow you to
determine which part is slipping, or too firm, but once all three
things are properly set it is a wonderful focuser.
One other thing to note, is that if you adjust things for the warm
temps of summer, and have cold Winters like I do, you will likely
need to adjust the tension harder for the Winter as the metal parts
will contract as it cools down resulting in the focuser potentially
slipping in the Winter.
Hope this helps,
--- In William-Optics@yahoogroups.com, Kelliot1@... wrote:
> I have attached below a solution I gave in April for the ZS105,
> assume has the same focuser. I hope this is helpful.
> I have, broadly speaking, been happy with my ZS 105. I say
> because although delighted with optics and build quality, I have
> been able to get the focuser to work as advertised.
> Out of the box it felt `notchy' and I found that there were places
> the tube travel where the fine adjuster would rotate without
> rotating the larger `gold' knob or moving the shaft. I have
> in vain to find owners who had managed to correct the problem and
> fiddled for hours with the large fluted screw and its central
> tensioning screw without success, maybe nobody else has had this
> problem, anyway, here is what I did, perhaps it will help somebody.
> I finally took the thing apart using the WO website instructions
> retrofitting a dual speed focuser and discovered the problem.
> is a threaded locking ring which (seems to) adjust the friction
> between the fine and course focuser which I very carefully
> with about 2 or 3 degrees of clockwise rotation. This needs to be
> tight enough to give free rotation of the `course/fine' knobs for
> their entire rotation and yet tight enough to give engagement. If
> you over tighten it will start to feel `lumpy'; too loose and it
> not engage all the way around.
> I had to make a couple of disassemble/I had to make a couple of
> right but `hey presto' the focuser now works as beautifully as I
> always hoped it would. Interestingly the black fluted screw does
> need to be extremely tight, as I have read elsewhere, just normally
> so, and the tensioning screw can be used to get the tube friction
> just right.
> As usual this process comes with a warning: be very very careful
> make only very small adjustments before checking all is ok.
> A (now) very happy ZS105 owner.