Combatting stiction, Yosemite 8x30 (1 Viewer)

[OPTIC_NUT]

I had noticed some focuser 'thunking' in the Yosemite 8x30 while
having an 'easiest to use' showdown, and I had opened a Celestron Nature
8x30 with the same issue and re-greased (the silicone around the O-rings
had polymerized to a gel/rubber) with success. So, then came time to go
for a cure on the Yosemites. How it went:

---The Yosemite 8x30 has the most solid focuser clamping and tightest
movement (ie, no wobble from left to right) of the clones I have. It also
has tighter fit than the two Celestrons or the Barska, and no hysterisis
as such. But...there is that hesitance, on first use.

---So I approached the focuser clamp. Obviously tighter, and more carefully
fussed-over in assembly. But:
--it's all potted-in with epoxy or some such, with tough adhesive even
in the setscrew wells....this thing is jealously guarded.
--the tightener slot is lightly cut and can't bear much torque The brass
is specially weak. The sign says 'no trespassing', maybe.

** So, I would have to use unpredicatable epoxy stripper or drill out the
setscrews and assert my Loctite scheme over theirs...
........time to button up and ponder, so as not to ruin things.

So...what to do?

The plastic ocular guide tube looks identical to that in the Celestrons.
My theory is: a polymerizer in the guide tube is polymerizing the
silicone grease into silicone rubber.
The remediation: 50 full focuser cycles to wipe the stuff to the limits
of focuser travel. Maybe the seal will go dry in the middle, but at least
it won't lurch.

So. That's all I did, cycle the focuser many times. It's much smoother now,
18 hours on. If I have to go in, in a year or 2 or 10, I'll probably have to
take a chance on drilling out the setscrews and actually fixing the grease.

 

[OPTIC_NUT]

I looked up stiction. Supposedly a 1946 shortening of "static friction".
I think of something a little more detailed, though. What I think about
is a static (starting) friction that increases with a time of disuse.

 

[OPTIC_NUT]

So I took the Yosemites out to see if the 'focuser-scrubbing fix' holds.
3 days on, I watched Great Blue Herons, Canada Geese, and Ospreys from the
esker on Foster's Pond. The fix holds, if I go through a full cycle.

The smoothness is back. The sharpness is better than the day I bought the binocs.
This was really obvious at 100 to 300 yds. I followed the herons around easily
and saw a lot of detail. Now the Yosemites pull ahead of the Celestron Nature 8x30s.
(but not before). Mechanically, their focuser is awesome...it just had that gelling grease.

So my faith in the Yosemites is somewhat restored, although it's un-nerving that it
takes a special procedure to get the best results. I could recommend them
again, but not without break-in instructions. It might be good general advice...
not sure. Reminds me of breaking in a baseball mitt back in 5th grade.
Awful one day, awesome the next.

 

[perterra]

So I took the Yosemites out to see if the 'focuser-scrubbing fix' holds.
3 days on, I watched Great Blue Herons, Canada Geese, and Ospreys from the
esker on Foster's Pond. The fix holds, if I go through a full cycle.

The smoothness is back. The sharpness is better than the day I bought the binocs.
This was really obvious at 100 to 300 yds. I followed the herons around easily
and saw a lot of detail. Now the Yosemites pull ahead of the Celestron Nature 8x30s.
(but not before). Mechanically, their focuser is awesome...it just had that gelling grease.

So my faith in the Yosemites is somewhat restored, although it's un-nerving that it
takes a special procedure to get the best results. I could recommend them
again, but not without break-in instructions. It might be good general advice...
not sure. Reminds me of breaking in a baseball mitt back in 5th grade.
Awful one day, awesome the next.

Best break in procedure I have found is just use them.

 

[OPTIC_NUT]

I don't believe this is a feature of all Yosemites.
Likely a bad batch of grease or a guide tube with
excess polymerizer.

Unless you're watching a stock-car race or a football game
from the front row, it could take years that way, and changing
distance range can give you a nasty 'speedbump' of caulking to get over.

I tried at 10 full cycles with an overnight rest. It isn't enough:there is still enough
residue to make sharpness elusive the next day. So there is a 'remaining glaze'. You can
say 'best way', but you'll need a few pairs of Yosemites in sticky-grease trouble to prove it.

I'm toying with the idea of a little drill-n-inject of something for the long-long term.
Whatever it is needs to survive an aging test.
The sliding surface is on the ID not the OD.

 

[stephen b]

Just saw this thread the other day and it was an opportune time to see it.

I have had a 6x30 Yosemite ( green ring original) that I have had for a few years. It does not get used a lot ( mostly fall hunting seasons in thicker woods) and I never had a problem with it sticking with the focus wheel. Then last week I noticed the same thing that is described above- a sticky almost jumpy feel to focus wheel. I thought to myself- oh, this does not seem good, my Yo is giving up the ghost. I called Leupold about it and they said just send it in and we will see what we can do, and if not we can send you out a replacement one. But they said that it would be a newer model one-not a Yosemite.

Well, I was thinking about sending it in and was not thrilled about it, because everything else I like about the binocular that I have. And then a couple of days ago, I came across this thread. And..... I tried the exact method of treatment described above by ON; and it worked really well. Enough so, that I do not think I will be sending them in to Leupold. They are now almost back to original focus feel.

The only thing that I did notice after trying this method that changed was the diopter setting changed by about 1/4 of the negative range that I am in. Not a big deal at all.

Now I am going to be mindful of putting the focus wheel on my Yosemite through its paces on a somewhat regular basis, even during ( or especially during) the times that they are not being used.

Big thanks to Optic_Nut for pointing this out and offering a cure.

 

[OPTIC_NUT]

What can I say:
I am a restless creature when it comes to defects in otherwise great stuff.
I gave up trying to buy perfect a while ago, in many categories.
It's been about 20-30 years of fixing new things around the house. I was miffed at
first that I had to, but it's not too hard and you don't have to wait years for the
makers to wise up. Who woulda thought, in the 21st Century?

I just checked again...sticky after a few weeks, but just one full cycle to make
them work smoothly again. The Celestrons are quite nice and the grease keeps,
but they don't have the same best-performance as the Yosemites on the focuser.

 

[curvecrazy]

I posted about this once before and I believe you responded on that thread but have you considered trying Moly Dry Film Lube? I believe the Yosemites are considered waterproof/resistant and therefore they seemed to me on the tight side what little experience I had with them in the store trying them out. You would want to use very little dry film lube. Probably apply one small drop at a time and do the same procedure you specify basically. There are various old porro prism binoculars I have brought back to "happy functional" with the dry film lube. The one I went too far and its so slick you can change the focus by pushing on the eyepiece bridge when in use. LOL But that was so sticky originally that it was basically unuseable or you might say "VERY fruSTrating" to use. I presume the grease had hardened with age inside. The dry film lube is like water and flows into very tight spaces. Thus its important not to use too much. It goes in wet and dries leaving a film on the surfaces. So you can apply the dry film repeatedly over several days and use your back and forth method. You might be surprised... Or I might have totally misunderstood what you meant here and I'm out in left field with no fly ball! 3

 

[OPTIC_NUT]

That would work normally....
Here's the nasty part, though:

The O-ring is on the INside of the occular guide tube instead of the side
you can see. And....the focuser clamp is pooped with epoxy, so I'd have to
drill out both setscrews in order to uncork the dang things.

Quite a puzzle. I've taken apart and Loc-Tite'd the sister focusers on the
Celestron and the Barska, but the defensive construction of the Yosemite
gives me pause. So here I am, cycling twice to unstick a nice focuser.
I though of a tiny drill hole and injection, but any stray solvent would get into
the inside air. Most vexing.

I ought to drill and do surgery, but it's easier and less raisky to prep the focuser.
If the O-ring shrinks and loses seal, that's fine by me. Removing (both per side)
pushed the Celestrons out of collimation, so something must remain. The
Celestrons I just gun-greased and put bak together better than new with LockTite
and no setscrews.