I'm in the market for a 400mm 2.8L. I'll probably buy new, but I'm open to picking up a good used one. Have improvements been made recently that I should make sure that I get one that was built a certain year or newer? Or are there future enhancements known that I should wait for? Also, does B&H ever run any specials on this lens? I understand that coupons are no longer publicly posted on this forum, but I sure would like to get the best deal possible.
Any advice on how to get the best lens for the least amount of money would be greatly appreciated.
Canon EOS 1D X & 1D Mark IV

