Weather sealed M42 lenses?

[Dores]

Are there any weather sealed M42 lenses out there, and how resistant are in example the cheap Helios lenses? When there are no electronics inside a lens, can it then be damaged by rain? I know that dropping it in the sea is not a good idea, but some quite heavy rain?

[aoleg]

I know no weather sealed M42 lenses. If water gets inside, you can get rust on aperture blades and condensation on optics. Mold and fungus may develop in consequence.