The last two times I've gone out with my Z6 and 24-70 S the inside of the lens has started to fog up so that it can't be wiped away. It's hard to see in the images but there also seems to be small spots in among the fog. This all disappears when I go home. When I shine a light through front lens element, after I've returned home, I can't see the fog or spots anymore. I've never had the lens out in heavy rain. The most was a light drizzle. It's never been in water. Is this simply condensation as a result of misty, humid mornings or is the fact that the fog is on the inside of the element a cause for concern?