Re: FINGER PRINT ON LENS

[Paul Schliesser <paulsc@eos.net>]

>Last Saturday the son of a close friend of mine, put his little finger on 
>the back element of my 35 Summilux AHSP, when I realized that I tried to 
>remove it with a dry microfiber cloth (according to  the Leica 
>instructions), but what happened was that the print wasn=B4t cleaned at all, 
>instead, the dirt was all over the back lens, since this is the first time 
>it happens to me,  I decided leaving it like that and ask for advice, my 
>question is :
>     
>How could I remove that dirt without removing (or scratching) the coating of 
>the back element ?

Jorge,

Try breathing gently on the lens to fog it with your breath. Then wipe it 
gently with your microfiber cloth before the moisture evaporates. Be sure 
that the cloth and your hands are clean, and wipe in a circular motion. 
If the fingerprint is oily and doesn't want to come off, try it several 
times to be sure it's clean. Always use a new, clean area on the cloth so 
that you don't deposit the old skin oil back to the lens from the cloth. 
Since you are in the rear of the lens, if your cloth touches the metal 
parts inside the lens, try not to touch the glass with those parts of the 
cloth that touched the metal, since the cloth may pick up a little bit of 
lubricant from the metal.

The acids in skin oil can etch the fingerprint into the lens coating if 
you leave it there for a long time, so be sure to get it off.

Most people clean their lenses like this often, so don't let this scare 
you. Even if your are very careful, you will end up occasionally touching 
the glass of your lenses, and sometimes you may get dirt or dust on them.

The reason that Leica says to use a dry cloth, is that getting any liquid 
near the edge of the glass can cause the liquid to seep inside the lens. 
Once the moisture gets inside, it will stay there. This can cause mold 
and fungus problems later. Breathing on it will not deposit enough 
moisture for this to be a danger.

- - Paul