Archived posting to the Leica Users Group, 1998/01/31

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Subject: Re: [Leica] Filters, again, very long.
From: Five Senses Productions <fls@5senses.com>
Date: Sat, 31 Jan 1998 11:05:06 -0800

So how do you clean your dusty and fingerprinted lenses?

Francesco


At 12:04 AM 1/31/98 -0500, TEAShea@aol.com wrote:
><< >What about things collecting in the micro-fiber and leaving scratches on
> >the glass? >>
>
>Actually, it is not an issue of scratching the glass, but scratching the
>coating.  Modern coatings are very hard, but older coatings were soft.
One of
>the first coatings was magnesium fluoride which was so soft that its was
quite
>impractical for the outside of front and rear elements.
>
>Microfiber cloth is poly - which is much harder than cotton.  The
advantage of
>micrfiber is that it is very absorbant and the fibers are so small in
diameter
>that any scratches are very small.  Additionally, the poly in the microfiber
>cloths is not as hard as modern lens coatings - but should not be used on
>older lenses with softer coatings.
>
>Of course the biggest problem is that any dust on the lens surface is rubbed
>into the coating by the cloth (cotton or microfiber).  Dust often contains
>silica - which is very hard and sharp.  Silica is harder than even modern
lens
>coatings and will leave scratches.
>
>Tom Shea
> 


Francesco Sanfilippo,
Five Senses Productions
webmaster@5senses.com

http://www.5senses.com/