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Manon 10x50 Deluxe 5 Degree Issue

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#1 DrJ1

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Posted 17 November 2020 - 07:06 PM

There have been favorable comments on this forum about Manon binoculars including, I believe, by Martin Pond.  I bought a used pair of Manon 10x50 Deluxe by mail.  There were undisclosed problems and I fixed all but one.  The left barrel was cocked slightly and that apparently led to poor collimation.  Fortunately, I was able to remove the barrel, clean the inboard side of the lens, and screw the barrel in perfectly.  The binoculars are bright and sharp, but there is an obvious defect on the left objecive lens that is not on the outboard surface (see photo).  The lines look like deep scratches, and perhaps they are, but I was not able to feel the scratches with my fingernail.  I scrubbed the inside of the objective with a soft lens cloth and lens cleaning solution and then again with iso propanol.  There was no change in the defect.  My questions are as follows:  Has anyone seen a defect like this? Could they be delamination lines from the binoculars being dropped? Is there anything I can do?  Can I buy the proper objective lens for a reasonable price? I have broken binoculars that I use for parts and considered trying to see if an objective bell would fortuitously fit, but I don't want to risk crossing the already damaged threads.  Suggestions would be appreciated.  DrJ1

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  • crop 8342 Manon.jpg
  • crop 8339 Manon.jpg


#2 pat in los angeles basin

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Posted 17 November 2020 - 07:12 PM

It's a delamination of the Canada balsam adhesive that joins the 2  objective lens components together. Old age more likely than a hit but it's possible. The "cure " is to separate (heat or a good solvent -xylene?)) and  rebond with a UV cure adhesive. If it doesn't affect the view too much (smaller than some of the ones I have), I'd live with it .    Regards, Pat


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#3 DrJ1

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Posted 18 November 2020 - 12:19 PM

Thanks Pat.  I think I'll live with the defect as I'm not sure I can detect it.  I have a pair of Scope 7x50s with severe delamination in one barrel.  The barrels on my Manon and Scope look to be the same size.  I may try to see if the good Scope barrel fits the Manon just to see what happens.  The two binocs have different manufacturer's codes.  Best regards, Joe



#4 markb

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Posted 18 November 2020 - 12:29 PM

There are excellent threads on seperating lens elements with balsam cement failures. This is a weird looking one, almost like the bubbling goes back to the original cementing process. The failures I've seen, and it's a tiny sample, are snowflake or crack patterns. You have to decide if the repair is really needed; I would assume the defect is affecting images, though.

 

DavidG is an authority on these things and I'd follow his posts.

 

A fairly comprehensive one is at 

 

https://www.cloudyni...rs#entry9365297

 

I still have a pair of WWII 10x80 flak objectives to properly recent with Noland UV cement, but I used an alternative for my Dad's 1952 Steinheil 6x30s. The cells were well machined, and kept the 2 elements of the objective well centered, so I was able to use a single drop of 3 in 1 oil to fill the area between elements. Fraunhofer objectives have nearly identical curves on the inner faces of the flint and crown, so surface tension of the oil sufficed to'hold' them together, and prevented the low contrast and lack of sharpness that would have resulted from using no optical interface between lenses.

 

Correct index optical fluid or gel would have been ideal, but this worked for me, the oil inex was likely close enough. The first repair lasted 10+ years. 

 

If you have to go to the trouble of decedent ingredients yours, I'd go a bit farther and do the correct Noland cement repair.



#5 pat in los angeles basin

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Posted 18 November 2020 - 12:37 PM

Yesterday, I pulled out of the closet, a pair of 7x35 swift sportstar , 8 deg to see if the mineral oil I used to replace the  failed  Canada balsam had separated. Checked by looking close to sun , and looking at the  lens at an angle to see If I could detect any difference between the 2 objectives. I Don't recall at this point which was has the oil spaced elements. Can't tell now after about 2 years of making the "repair". Good enough for me. Still amazes me the a drop of oil can substitute for the bond.  Pat


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#6 DrJ1

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Posted 18 November 2020 - 02:11 PM

I recall in grad school doing calculations of how a thin, relatively plastic layer between two rigid solids is constrained from deforming and it takes great force to separate the rigid solids.  Professor Drucker was a pioneer in such work.  The calculations were relevent to my thesis work on tungsten carbide constraining the deformation of the thin cobalt layer in cemented carbides.  I'll live with the Manon defect for now.  Thanks to both of you. DrJ1



#7 MartinPond

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Posted 19 November 2020 - 12:17 PM

Probably most 10x50 objectives are the same

  from that era and from Japan....

but it's hard to say if the focal length would match

 up just right.   Maybe if both sides were replaced,

from a pair sold as parts-or-repair, with the

focuser arm broken or something?

 

 

That happens in 3 yr old binoculars and 50 year old ones..

I wonder if they were set down on a hot porch rail

some time ago..



#8 Senex Bibax

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Posted 19 November 2020 - 12:35 PM

Mark a line across the sides of the lenses with a Sharpie or similar before you separate them. That way you can make sure they are aligned the same way when you reassemble them.



#9 DrJ1

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Posted 19 November 2020 - 04:25 PM

Mark a line across the sides of the lenses with a Sharpie or similar before you separate them. That way you can make sure they are aligned the same way when you reassemble them.

Good suggestion.  Even when I've tried that in the past, sometimes I mess up and the binocs are slightly out of collimation.  I had to look at stars while turning the bell slightly with my hand to fine adjust.  Thanks, DrJ1

 

Probably most 10x50 objectives are the same

  from that era and from Japan....

but it's hard to say if the focal length would match

 up just right.   Maybe if both sides were replaced,

from a pair sold as parts-or-repair, with the

focuser arm broken or something?

 

 

That happens in 3 yr old binoculars and 50 year old ones..

I wonder if they were set down on a hot porch rail

some time ago..

Thanks Martin.  I've read your many posts and have a watch list for when I go to thrift shops and pawn shops.  COVID has unfortunately hindered my hunting.  DrJ1

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