they are not scratch resistant
my old 80-200 was bought from a guy who never used lens caps and
the front glass was still about as good as it gets. Its really
hard to scratch that glass as its very hard and so is the
multicoating they put on it. I wouldnt suggest trying it of
course, but its not by any means fragile
the paint can get a little wear, far easier than the glass, but
thats pretty cosmetic.
If you want to keep the lens looking like new for collector purpoes
or something thats one thing, but nearly every serious wildlife
photog ive met who has a bit supertele like a 500 or 600, has alot
of wear on the lens.
Its just something that happens from taking it out into the wild
but thats what you pay all that money for.
Plus once you get that first scrach, then other ones dont matter as
much. My new 300 2.8 IS is still mint so I dont like to set it on
the ground. My old non IS lens was all scratched up already. I
woulnd just lay it down on the ground and no worry. It was alot
easier since I try to get a towel or something to lay the new one
on.
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