I have a pair of Pentax 10x50 binocs, about 1986 vintage I suppose
Once at an Adelaide GP one of my enthusiastic friends decided my binocs were covered in fuel and did his best to wipe off the strange colouring effect (unobserved by me and others)
To whit I now have a damned fine pair of binocs lacking coatings of light filtering goodness
Needless to say I was a bit 'annoyed' about this but there was nothing I could do/say, he was, in all honesty trying to do the right thing..........
Anyways, I have always wondered if it was repairable?
FREE COATINGS JUST FOLLOW STEPS PUT A MATCH NEAR THEM AND THEY'LL BE ON FIRE AND THE COATINGS WILL BE FREE AND YOU WILL BE ABLE TO CHOOSE ANY COLOUR OF COATINGS AS LONG AS ITS BLACK
NO WAIT THATS RIGHT YOUR FRIEND GOT RID OF THE PETROL DIDNT HE
no siriusly i think you can because the objective lens is basicly like a refracter telescope AND THIS TIME DONT get shiny coatings
I imagine you could have them re-coated but.... be a bit expensive. Have a look on Surplus Shed, there may be a set of lenses on the list that would replace the damaged ones. Best thing I can suggest.
In practice no, you put them in the bin and buy another one.
To recoat a lens is possible in principle - provided it is not cemented - if it is cemented, it goes in the bin.
- grind the coating off using abrasives,
- re-polish and re-figure the lens,
- re-centre the lens (the result will also be a smaller aperture lens)
The problem starts with the modern multi-layer dielectric coatings based on zinc cryolite, which are harder than glass and can only be removed by grinding them off. The trouble is, the underlying glass being softer will also be abraded and the lens will become thinner as a result.
Now the killer - in doing the above, the lens will be thinner than it was, and also smaller in diameter. The thickness matters for optimum achromatism - change that and the lens will not work as well as it did. Theoretically you might be able to tweak the design parameters to find a solution that fits with the glass you have left, but it won't be optimal - ie the lens is never going to work as well as it did before.
Lastly the cost of doing all this exceeds the cost of a new lens, which is why no-one does it in practice. Cheaper to get a new one.
In practice no, you put them in the bin and buy another one.
To recoat a lens is possible in principle - provided it is not cemented - if it is cemented, it goes in the bin.
- grind the coating off using abrasives,
- re-polish and re-figure the lens,
- re-centre the lens (the result will also be a smaller aperture lens)
The problem starts with the modern multi-layer dielectric coatings based on zinc cryolite, which are harder than glass and can only be removed by grinding them off. The trouble is, the underlying glass being softer will also be abraded and the lens will become thinner as a result.
Now the killer - in doing the above, the lens will be thinner than it was, and also smaller in diameter. The thickness matters for optimum achromatism - change that and the lens will not work as well as it did. Theoretically you might be able to tweak the design parameters to find a solution that fits with the glass you have left, but it won't be optimal - ie the lens is never going to work as well as it did before.
Lastly the cost of doing all this exceeds the cost of a new lens, which is why no-one does it in practice. Cheaper to get a new one.
at least there not covered in fuel any more
it might make wazza45s sad
