Quote Originally Posted by DaveOttawa View Post
There is really no optical downside to coating, it wll not affect sharpness as someone implied above - although disassembling the lens to coat and reassembling slightly off obviously could.
I think it was Arax who stated on his site that Multi-coating some older lenses could actually be counter-productive, and that single coating was often a far better option. He no longer offers a coating service unfortunately.