So everybody is saying "lenses are more important then bodies" which of course is true. But since lenses like the 12mm, 75mm, 12-35, 35-100, 25mm are very expensive, I wonder what is the durabilty of lenses like this ? With durability I mainly mean "built quality". Can "modern" lenses last a lifetime ? Do they need maintenance if you always take good care of them (body caps always on, filter, no walking in bad weather) ?