[Leica] coating and water

[Erwin Puts <imxputs@knoware.nl>]

J.L. Adams wrote  most sensible about lenses and their coating's resistance
to abrasive actions.
Indeed modern coating techniques  use a process of  ion-assisted deposition
of cold substrates to deposit a thin film on a glass surface. The older
type of physical vapour deposition of heated substrates has the same
characteristics.  The coating cannot be washed off by water, salt or
otherwise and even the length of time of being immersed in water is of no
importance. To give an autentic story. Mr Crawley from BJP once dropped a
Summilux-M 50mm into the sea after taking pictures on a boat. SIX months
later the lens was recovered, being exposed to salt water all the time. He
cleaned the lens, lubricated it and image quality was as before. This is
recorded and not a hear say story.

Erwin