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Thread: removing ruined coating on old lenses?

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    Senior Member dude163's Avatar
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    removing ruined coating on old lenses?

    Hi all
    i have a bad cold so I decided to tear down my foggy and hazy 90 elmar from 1958

    I got it all apart and cleaned up, the front and middle elements are fantastic, the rear was very oily and hazed over, i washed it numerous times and it appears the coating on it is the problem , its half gone and half of it is murky or decayed . Its not fungus ( I dont think) because it looks like when you remove sticky tape and it leaves a slight residue , and it only shows up after the lens is assembled , weird , it must be once the 3 elements start to do their job it amplifies the problem


    Any hints/tips to clean it up further or remove the coating itself? cheers

    Robert

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    Senior Member dude163's Avatar
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    Re: removing ruined coating on old lenses?

    here are 2 images after the cleaning



    this one is a B+W JPG right out of the camera



    oh and both ISO 2500!

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    Re: removing ruined coating on old lenses?

    If it works as is, leave it.

    If its a bother, determine if it is some extraneous (like a sticky tape residue) that causes the blemish by trying 1. Ethanol 2. Acetone (nail polish remover) 3. Petroleum ether (each time wiping and drying with ethanol after done).

    If all else fails, if you really want to get rid of a single coating, use Ammonia (and thorough cleaning afterwards). Keep in mind Ammonia also takes of a tiny bit of the glass itself.

    Oh, if you have a cold/blocked nose don't do it as you can't smell anything even in a well ventilated area.

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    Senior Member dude163's Avatar
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    Re: removing ruined coating on old lenses?

    Thanks Vivek , its about 5 x better than before as it was quite soft and low in contrast.

    I was actually astounded how clear the front element was after cleaning it in detergent and then rubbing alcohol, its like a large contact lens!

    If I get the urge to take it apart again Ill try the nail polish remover, with 3 gals in the house we have loads of it

    Cheers

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    Re: removing ruined coating on old lenses?

    Try 99% Isopropyl Alchohol on a Q-Tip. This worked on a Sonnar with damged interior coating. It was soft-coated.

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    Senior Member dude163's Avatar
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    Re: removing ruined coating on old lenses?

    ok I will, cheers

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    Senior Member dude163's Avatar
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    Re: removing ruined coating on old lenses?

    Now that the lens has dried out over a few days, it appears that the blemish has faded a lot, Im thinking it might actually be the cement between the back 2 elements, I thought my Elmar was a triplet , but its a triple group , FOUR element configuration

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    Re: removing ruined coating on old lenses?

    Don't forget to polish the glass with cigarette ash

    (an actual recommendation by Zeiss for removing fungus from lens elements)
    M262 ZM 25/2.8 35/1.4 50/2 85/2

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    Senior Member dude163's Avatar
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    Re: removing ruined coating on old lenses?

    Another at ISO 2500


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    Re: removing ruined coating on old lenses?

    It looks fine to me.

    I picked up a $15 Canon 135/3.5 in Leica mount, later black LTM lens. The Canada Balsam had failed, the middle group was opaque. Separated the elements, used 99% Isopropyl to clean the residue, and used index matching oil from a microscope to replace the balsam. Basically, the surface tension was enough to hold the elements together and the index matching oil prevents Newton's rings. Still looks good, all these years later.

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    Re: removing ruined coating on old lenses?

    Canada balsam. Should not be difficult to access for Robert.

    I had to import this stuff. Dissolves nicely in Petroleum spirit. Leave the solution for a month or so to settle the particulates. Micro syringe from the top to use. Just make sure there are no bubbles and dust particles while setting the lens elements. Lots of help online if you search.

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