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Vintage Manon maintenance: noob plea for help

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#1 Eiderlight

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Posted 21 January 2021 - 01:10 PM

After reading some glowing reviews of vintage Manon binoculars on Cloudynights, I went and bought a pair of 10x50 5.5° ... they arrived today, and are indeed beautiful. It's such a delight to hold that history in one's hand and look out at the world through that classic glass.

 

But of course there's a reason why I shouldn't have nice things....

 

So as I was trying to see how close they could focus, I turned the focus dial so much that the center screw and eyepiece apparatus just unscrewed right out. (Apologies if I'm not using the right terms ... I know next to nothing about binoculars!) I screwed them back in, but it didn't seem right, and I promptly spent the next two hours fiddling with them.

 

Either too much of the center screw seemed visible or else I overcompensated and ended up with too much of a gap underneath the focus dial, which seemed like a surefire way of getting dust and gunk down into the center screw housing.

 

Finally, with a sense of dread that this marvelous object had survived for decades only to have the misfortune of ending up in my clumsy hands, I stopped. Attached is a picture of what they now look like with the focus at infinity. That center screw/eyepiece still doesn't set flush all the way down into the depression below it.

 

Did I do something wrong? Should I just send them for maintenance to someone with expertise?

 

Thank you!

 

manon.jpg



#2 Rich V.

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Posted 21 January 2021 - 01:56 PM

There should be a brass screw accessed from the opposite (objective) end of the hinge that holds the focuser/ eyepiece bridge assy locked in place so it can only travel so far.  Perhaps this screw is missing?

 

When replacing the focuser/bridge assy back into the hinge from the eyepiece end, you may have to turn the focus knob one way or the other to extend the central shaft on its helical threads so that sufficient inward/outward focusing range is achieved.  It may take several tries to get the correct range of motion.

 

Rich


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#3 harbinjer

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Posted 21 January 2021 - 02:02 PM

Everything that Rich V. said is right.  If the screw is missing you can try to replace it, or you can live with knowing that you can't unscrew it too far.


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#4 Eiderlight

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Posted 21 January 2021 - 03:00 PM

Thank you both very much.

 

 

Two questions: is there a simple way for me to know what the correct range of motion ought to be? And there is a screw in the center of the shaft at the objective end ... is that the one that's supposed to be holding the focuser/bridge assay in place?

 

manon2.jpg



#5 Eiderlight

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Posted 21 January 2021 - 03:09 PM

And one other thing ... how smooth/easy can I reasonably expect the focus to turn?

I have a random pair of Selsi 8x40s from the 1970s and the focus turns like a dream. On the Manons, it turns smoothly but slowly,  requiring significant pressure.

Thank you!



#6 asphericalaberration

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Posted 21 January 2021 - 03:31 PM

>requiring significant pressure

 

On vintage bins, it's common for the lubricants to have hardened over the years. If bothersome, you can remove the focus bridge (which is already loose, from the sound of it), dissolve the older lubricant (e.g., in lighter fluid or the like), and replace the lubricant (ideally with damping grease, which is hard to get in small quantities, or more practically with a non-lithium grease).


Edited by asphericalaberration, 21 January 2021 - 03:32 PM.

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#7 harbinjer

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Posted 21 January 2021 - 04:26 PM

Thank you both very much.

 

 

Two questions: is there a simple way for me to know what the correct range of motion ought to be? And there is a screw in the center of the shaft at the objective end ... is that the one that's supposed to be holding the focuser/bridge assay in place?

 

 

There isn't really a "correct" range of motion, only really a useful one. You want your infinity focus to be achievable and then some closer focus.  The missing screw is under the front hinge. Remove the screw and cap in front an take a look in the hole, if you care to look/fix it.


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#8 Eiderlight

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Posted 21 January 2021 - 05:30 PM

This is very helpful. Much appreciated to all.

 

I'm going to get some damping grease and get to know my binoculars!



#9 pat in los angeles basin

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Posted 21 January 2021 - 06:26 PM

Yes to the grease getting thicker with age (and  cold temps too!) . Not uncommon for a cheapskate fixer to add a bit of a mild solvent to thin the grease a bit  or better yet clean off the old  crud and replace with a decent synthetic. Ideally  you need to get the  correct "damping grease" from someone  like nye lubricants (also available on *bay). 

 Regarding the focuser - I usually start with the focus wheel turned out  somewhere  between 3 to 4 full turns, then (carefully) insert the eyepiece /focus arms assembly then turn the focuser a tiny bit while pushing down on the  eyepiece assembly to engage the gearing worm screw. To start- turn down the focuser with the EP (eyepiece assembly) removed. I make a mark with a pencil at the 12 noon position of the  wheel, then turn out  the requisite turns, then  correctly seat the EP assembly- careful  with getting both eyepieces  seated the same amount down on the eyepiece tubes that are  part of the binocular body and give the wheel a light turn to engage (clockwise). If everything seems to be cooperating, continue turn down till the  whole thing suddenly  won't allow any further turning. Make not of where the collar  of the focuser is sitting in relation to the recess in the focus wheel. I f it doesn't seat itself, reverse the procedure to pop the EP assembly out and give the focus  wheel another 1/2 turn out to allow for deeper travel. That is IF you need the travel.                                                                Regards, Pat

.


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#10 DrJ1

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Posted 21 January 2021 - 09:31 PM

I had a similar problem with a B&L Custom 8x36 National Audubon binocular.  I was focusing through the full range and, to my shock, the entire occular assembly fell out.  I fortunately caught it with no damage (I played centerfield in college lol.gif ).  After I fixed the problem, I put an elastic band (akin to a girl's pony tail elastic) on each side of the occular assembly so it could not fall off if my repair was inadequate.  I have several Manon 10x50 binoculars and I love them.  BTW, I'm printing out pat's advice for future reference.  DrJ1


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#11 FrankL

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Posted 22 January 2021 - 06:13 PM

“There should be a brass screw accessed from the opposite (objective) end of the hinge that holds the focuser/ eyepiece bridge assy locked in place so it can only travel so far.  Perhaps this screw is missing?

When replacing the focuser/bridge assy back into the hinge from the eyepiece end, you may have to turn the focus knob one way or the other to extend the central shaft on its helical threads so that sufficient inward/outward focusing range is achieved.  It may take several tries to get the correct range of motion.”

 

This is good advice. And if you’re lucky, the brass screw that secures the focused assembly inside the hinge tube may just have become unscrewed inside the tube and still be there. There’s usually a lot of grease in the tube which is why it doesn’t rattle or drop out. I suggest you remove the objective end hinge center caps and inspect the inside of the hinge tube to see if that brass screw is still inside. I’ve attached a picture showing how your CF mechanism is most likely built. On the right side of the picture you can see the two objective end center hinge caps and the brass screw. Note that if you’re able to reinstall the screw, it will probably be reverse threaded and screw in counter-clockwise.

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  • CFjpnse (640x410).jpg

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#12 Rich V.

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Posted 22 January 2021 - 06:53 PM

As always, Frank, waytogo.gif




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