[Leica] Are UV filters "safety glasses" for the lense?

["Austin Franklin" <austin@darkroom.com>]

Most humans don't walk around all day with safety glasses on.  Though a lot
of people wear glasses, and the glasses happen to be safety lenses, if given
the choice, I believe they would prefer not to wear them.

The human eye has protection mechanisms, automated cleaning mechanisms, and
different operational requirements than our camera lenses.  The eye has an
eye lid that closes when some harm is on the way...and the eye has the human
body viewing and evaluating any dangers, so the eye can be protected.  Of
course we watch our equipment, but I'd venture a guess most of the potential
damage to a lense isn't caused while we are watching...

The eye also has self cleaning mechanisms.  One of them being the eye
lids...as well as a constant fluid siphoning away any small debris.  Large
debris, we can pull out with our fingers.

The eye is also self healing, and is quite soft.  On the contrary, the lense
elements need to be lived with or replaced when damaged, and are quite hard,
so certain damage might occur more easily.

The eye and the camera lense have different requirements of operation too.
The camera lenses that we use on our Leicas take still images.  As such, any
defects are readily observed in the resultant image.  The eye only views
life as moving, never seeing the same 'frame' again, and as such, just like
TVs and VCRs, the image quality doesn't have to be anywhere near as good,
and minor damages will never be observed.