I have had people tell me that their camera took a
hit but thankfully the filter took the trauma... with
the dented filter as proof. but that was from being
banged around and not from a fall.
like someone switching lenses in a rush and having the
lens fall off from not locking it into place properly. and to
be honest, a lens filter does little to protect something
like that. a lens filter with an auto-deploying airbag...
now there's an idea!!!
it's better to keep your head in check and think it
through even when trying to grab a quick shot.
make sure everything is locked in place and your camera
strap securely around you or wrapped around your arm.
for me a lens filter is best for preventing smudges on
your lens. one good example on when to use a protective UV
or skylight filter is shooting kids who like to poke lenses
with sticky fingers. other times I don't use a filter and
prefer a lens hood for bumper protection.