I might be crazy but I have always felt that my 24-70 2.8 L mark II doesn't focus as sharply as I would like. There is also some dust in the lens and I managed to damage some of the lens coating at the periphery of the lens but have been told it shouldn't affect image quality. I'd like to know the best place to send the lens and have it checked out. I have seen canon has its' own service center and there are also a lot of third parties doing authorized service also. What would be the best cost effective place to send the lens and how do they deal with the lens coating issue? New element, re coat the element, costly? I bought it on Amazon so sending it back to the vendor really isn't an option. The lens is also out of warranty.