lubricating stiff focus (1 Viewer)

[sssboa]

Hi,

So I have some Japanese binos with very stiff focus.

What's the remedy?
Rinse everything with naphtha or alcohol or maybe "goo gone"? Then put on new grease?
Not easy to do.

Or maybe put some silicone oil on the old grease or something else to thin it? But what exactly?

Would be grateful for ideas, especially well tested ones.

Thanks guys!

 

[Alexander Stöhr]

Hello,
are they new? Internal focus or external focus, with moving outer parts, either oculars or rarely the objective lens (like the Zeiss 10 x 40 Dialyt). If your bino has external focus, then it becames (slightly) easier with time (and use).

Yes, there are experts that can fix issues themselves, but my advice is (true in more than 90%): let an expert do it: send it to the manufacturer or to some optic service. Dont try this at home!

What is the englisch word for "verschlimmbessern"? Google says "worsen better". No offense to you, maybe you are one of the few experts, that have vast experience in this field and have repaired /fixed optics at least a few times before. If not, let an expert do it

 

[sssboa]

Hello,
are they new? Internal focus or external focus, with moving outer parts, either oculars or rarely the objective lens (like the Zeiss 10 x 40 Dialyt). If your bino has external focus, then it becames (slightly) easier with time (and use).

Yes, there are experts that can fix issues themselves, but my advice is (true in more than 90%): let an expert do it: send it to the manufacturer or to some optic service. Dont try this at home!

What is the englisch word for "verschlimmbessern"? Google says "worsen better". No offense to you, maybe you are one of the few experts, that have vast experience in this field and have repaired /fixed optics at least a few times before. If not, let an expert do it

They're old binos from the 1960's and 1970's, Yashica and Pentax, not worth sending anywhere. I already cleaned some of them inside of fungus and mould.

 

[Stephen Prower]

They're old binos from the 1960's and 1970's, Yashica and Pentax, not worth sending anywhere. I already cleaned some of them inside of fungus and mould.

Yashica 8x30:

Cleaning: I clean both (i) focusing wheel threads and their receiving gooves and (ii) focussing screw threads and their receiving grooves with lighter fuel. I apply the fuel with cotton buds; wipe it off threads with a tissue, or off grooves with a cotton bud.

I am in the UK. I use 'Clipper' Universal Lighter Fluid. From memory I buy it in Asda. The chemical name of the fluid is described on the dispenser as 'Petroleum Distillate'.

Lubrication: I use Nyogel 767A damping grease for both wheel and screw. It is hard to buy in small quantities. Other posters may have tips of the sort of companies that use it in commercial quantities and might help with a couple of grammes.

I experiment with different thicknesses of grease. I may apply different thicknesses to wheel threads and focussing screw threads. It can be a time consuming exercise of repeated 'Clean - Re-lubricate - Re-try'.

I personally would prefer a less viscous grade of Nyogel for the Yashica, but I work with what I have got. Other people might be fully satisfied with the 'weight' of operation of the focusser that I have managed to achieve.

Possibly I use too much grease. People sometimes advise to use only a 'smidgeon'. But how much is a smidgeon? One man's 'smidgeon' may be another man's 'dollop'.

A friend advised that I need only apply lubricant to the threads: 'It would work its way around'. I have now followed his advice for a couple of 'treatments'. I haven't experienced any problems to date.

Comment: I hope I have got the technical terms right. I use plain 'screw' and 'receiver' myself, but could not confirm on the web that these are the correct terms.

I hope this helps


Stephen

 

[Stephen Prower]

They're old binos from the 1960's and 1970's, Yashica and Pentax, not worth sending anywhere. I already cleaned some of them inside of fungus and mould.

I see that there are 50gm tubs of Chinese damping grease offered at about £5 on the web. Do an Ebay 'All categories' search on string <damping grease>. If you do buy a tub, let us know if it works for you. If it doesn't work, then in my experience lighter fuel will clean off damping grease. Stephen

 

[sssboa]

Yashica 8x30:

Cleaning: I clean both (i) focusing wheel threads and their receiving gooves and (ii) focussing screw threads and their receiving grooves with lighter fuel. I apply the fuel with cotton buds; wipe it off threads with a tissue, or off grooves with a cotton bud.

I am in the UK. I use 'Clipper' Universal Lighter Fluid. From memory I buy it in Asda. The chemical name of the fluid is described on the dispenser as 'Petroleum Distillate'.

Lubrication: I use Nyogel 767A damping grease for both wheel and screw. It is hard to buy in small quantities. Other posters may have tips of the sort of companies that use it in commercial quantities and might help with a couple of grammes.

I experiment with different thicknesses of grease. I may apply different thicknesses to wheel threads and focussing screw threads. It can be a time consuming exercise of repeated 'Clean - Re-lubricate - Re-try'.

I personally would prefer a less viscous grade of Nyogel for the Yashica, but I work with what I have got. Other people might be fully satisfied with the 'weight' of operation of the focusser that I have managed to achieve.

Possibly I use too much grease. People sometimes advise to use only a 'smidgeon'. But how much is a smidgeon? One man's 'smidgeon' may be another man's 'dollop'.

A friend advised that I need only apply lubricant to the threads: 'It would work its way around'. I have now followed his advice for a couple of 'treatments'. I haven't experienced any problems to date.

Comment: I hope I have got the technical terms right. I use plain 'screw' and 'receiver' myself, but could not confirm on the web that these are the correct terms.

I hope this helps


Stephen

Great, thanks.
I lubricated photo lenses before so I have greases- PTFE and Japanese white grease, many grades of viscosity.
With binoculars there's not that much need to care as the grease won't get on glass or on aperture ring so I use on both parts, in photo lenses only on one part. So far I used photo lens grade 40 (for metal zoom helicoids) on Soviet Tento 10x50 from 1989, I just had that grease at hand. But with those Tentos it was just opposite to the Japanese binos, Tentos seemed not dumped enough felt like there was no grease at all, but they had black grease, or rather it had turned black with age. Wasn't really possible to remove it from deep inside the shaft, I bet it mixed with my PTFE grease but it is better now.
That Nyogel 767A. I see it shipped from the USA so I don't bother.

 

[Stephen Prower]

sssboa

Difference between focussers of Soviet Porros and Japanese 'Golden era' Porros

Snap! I discovered the difference between the focussers of Soviet Porros and Japanese 'Golden era' Porros when I came to sort out a Tento BPC 7x35 Porro. The Tento focusser was very free-moving but mechanically not smooth.

The problem with quite a few Japanese focussers was, by contrast, that they were too stiff. In some cases I actually thought that the cause might not have been wholly that they had become stiffer with the aging of the grease; the stiffness was part also an inherent feature of their design, namely the stiffness flowed from the designer's choice of pitch for the threads of the wheel or screw.

[There was also mechanically a difference in the design of the Tento's focusser: the wheel of the focusser did not turn in its own separate threads; it turned the focussing screw directly.

I remember also that, to take another Soviet-era binocular, although the design of the focusser of the Komz BPC4 8x30 is mechanically different to the design of the Tento, it is similar in that the wheel also does not turn in its own separate threads]

But to point! Whereas I was lubricating the focussers of the Japanese binoculars sparingly with damping grease in order to make them turn more freely, I had to add plenty of damping grease to the focusser of the Tento before it would turn at all smoothly.

The Tento focusser then, to my utter surprise, changed completely from a goose into a swan (or should I say, from a frog into a Prince, or whatever!): it now turned smoothly, progressively, and with just the right weight for me*.


Stephen


* Ie the explanation 'Soviet binoculars were designed to be usable at temperatures of -40*C' had nothing to do with the original 'sloppy' focussing of the Tento -- Unless the sloppy focussing was a deliberate response of the assemblers of the Tento to such temperatures to use little or no grease at all

 

[Alexander Stöhr]

They're old binos from the 1960's and 1970's, Yashica and Pentax, not worth sending anywhere. I already cleaned some of them inside of fungus and mould.

Hello,
sorry for my late reply. I just realized by your answer, that you have experience with "cleaning and more" in binoculars. And the expert answer from Stephen was the one you needed.

 

[Stephen Prower]

Alexander

You kindly accord me expertise!

I take or send new binoculars back for repair under
guarantee to the shop or manufacturer.

Otherwise I follow your sensible advice, and have twice sent
a faulty binocular for repair to a professional repairer.

The main exception is that I have learned by myself how to
disassemble and relubricate* the focusser of a few old
Japanese Zeiss-pattern, or Soviet models of full-size Porro
binocular. If a curious--in the sense of 'Curiosity killed
the cat'--previous owner has 'decollimated' a binocular by
unscrewing the objective barrels, I will of course try to
restore the barrels to their original setting.


Stephen

* Posters on the Forums have been most helpful by recommending lubricants. One poster generously gave me a portion of damping grease from his stash

 

[Stephen Prower]

Sssboa

Carton 10x50

1. Further to my original post, I have just now relubricated a Japanese Golden Era Zeiss-pattern 10x50 Porro that has the same focusser mechanism as the Yashica 8x30. The focusser was unacceptably stiff. I used Nyogel 767A damping grease to lubricate both the threads of the wheel and the threds of the focusser.

I applied a 'smear'--in my terms a very thin coating-- of Nyogel to the threads of the wheel, and two smears to the threads of the focusser*. I did not apply any lubricant to the receiving threads of the wheel or focusser, but let the smears of lubricant to the turning threads work their way around the receiving threads.

The result was satisfactory.

Nevertheless, as I said in my initial post, as a matter of personal taste I would have preferred to use a slightly less viscous grade of Nyogel. I continue to suspect that some mechanical factor such as the pitch of the threads limits how far one can reduce friction by thinning the coating of lubricant. If so, that leaves as I see it only the resource of reducing the viscosity of the lubricant.

I did not go on to experiment by adding more smears. I have an unreliable memory from increasing the thickness of the coating of lubricant of other binoculars in the past that adding more smears of damping grease led, perhaps contra-intuitively, to increased friction.

Variable friction

2. I stuck to essentials in the original post, but I take the opportunity of this update to add a detail from my experience with relubricating two binoculars where the friction of the wheel or focusser increased at a certain point as the wheel turned.

The increase of friction was not great, but it was so irritating that it put me off picking up the binoculars to use if there was any other binocular that I could pick up instead of them.

I put the increase of friction down to wear caused by the preferential use of the binocular by its previous owner to view birds within a particular range away from him/ her.

But it occurred to me that the cause might rather instead be the differential build up of some sort of coating of residue from the lubricant of the wheel or focusser.

So I intensified my cleaning of the threads of the wheel and focusser at the point where I estimated the increase of friction occurred.

All I can say is that the irritating increase of friction of the wheel of the first binocular was noticeably smoothed out, and that the increase of friction of the wheel of the second binocular disappeared.


Stephen


* The applicator was one of those fancy toothpicks that come with a brush-end

 

[Stephen Prower]

ssboa

Inherent stiffness of focussers

Here's ZeNiTh-PbArM on the inherent stiffness of the focussers in some binoculars (Post #18). He/She's referring to 'some Roof binoculars', but the explanation is equally likely to apply to all binoculars:

Bushnell Legend M sticky focus wheel

I gave my mother a brand new set of Bushnell Legend M 8x42 binos. The focus ring is hard to turn. I was wondering if I could use Jig a loo, which is a dry silicone lubricant to loosen it up? Any advice?

www.birdforum.net

To paraphrase ZP's explanation, the inherent stiffness of the focusser of a binocular is determined by the clearance between the threads, which is determined in turn by the permitted figure of machining tolerance, and the mix & match of parts.

Stephen

ZP's word 'lap' is probably my word 'smear'

​

 

[Stephen Prower]

Lubricating two examples of the same model of 1960s Porro binocular


I apologise if the number of followers of the Forum who are into fettling old Porros with stiff focussers is limited.

My excuse for a long report is that in my experience it can be hard to find encouraging examples on Bird Forum of how much lubricant--as opposed to what lubricant--someone has successfully applied to impove the action of the focusser.


1. I mentioned at Post #7 in the context of a circa 1980s Soviet Porro binocular (Tento 7x35): 'I had to add plenty of damping grease to the focusser of the Tento before it would turn at all smoothly'.

On the other hand, I mentioned at Post #10, in the context of a 1960/1970s Japanese Porro binocular (Carton 10x50): 'I have an unreliable memory from increasing the thickness of the coating of lubricant of other binoculars in the past that adding more smears of damping grease led, perhaps contra-intuitively, to increased friction'.

Recently I had the opportunity to test the memory that increasing the thickness of the coating of damping grease of a Japanese 1960/70s Japanese Porro binocular might increase, rather than further decrease, friction.


2. I recently bought a Swift Triton 7x35 MkI No 748 on Ebay. I cleaned the focussing screw and receiver. There was then (i) a lag before the focussing screw bit, and (ii) an occasional highly disturbing noise from the internal mechanics of the wheel. The noise was consistent with the wheel's turning in ball bearings (rather than screw threads)*. It was the sort of noise that I believe, from how cyclists describe it, is made by a damaged cage or ball bearing.

I lubricated the focussing screw with one or two smears of damping grease. The screw then turned smoothly, and I had a usable binocular. The mechanical noise did not occur sufficiently often to worry me, certainly in the short term (In the long term I was resigned to the fact that the focusser was on the way out). The lag was still obtrusive, but could be managed by a change of technique.


3. I decided nevertheless to seek out a mechanically fully sound example of the Swift on Ebay, and quickly succeeded in buying one that functioned properly in all respects. The focusser did though turn too stiffly for me, so I again lubricated it, as in the case of the first Swift, with one or two smears of damping grease. The focusser then turned with the right weight for me.


4. A couple of days ago it occured to me that I now had nothing to lose by trying out the application of more smears of damping grease to the focussing screw of the first Swift Triton.

I didn't believe that it would make any difference to the weight of operation of the screw, save as I thought to stiffen it, but what ho!

And I had the kit to do he job ready to hand, and had become fully familiar with using it.

In fact with each successive application the focusser did not move less freely.

My inhibition against adding more grease was removed.

So bearing in mind that damping grease is intended for smoothing out the relative motion of surfaces in shear, such as smoothing out lags, I went on to apply a total of 4 to 5 smears, and then tested the result.

It was hard to believe, but not only had the lags been eliminated, but also the occasional mechanical noise.

I can just about understand, as above, why the lag before the focussing screw bit disappeared; but in no way at all can I understand why the highly disturbing noise from the internal mechanics of the wheel disappeared also. I leave the fact a total mystery**.


5. The second, and now the first also, Swift Tritons continue to perform impeccably to this day.

Two identical binoculars, one fettled with a minimal one or two smears of lubricant; the other with a generous five to six smears, nevertheless in each case manifest the same good performance.


6. I qualify that the treatment of the two Swifts may take time to settle down!



Stephen


* I don't like to guess at ball bearings. But I can't get into the interior of the focussing wheel to see what it might otherwise, apart from screw threads, turn in

** I don't see any channel of communication between the focussing screw and the internal mechanism of the focussing wheel whereby excess damping grease could have percolated through from the screw to the internal parts of the wheel