I had the same suspicions about MLU, which is part of the reason I bought the EF in the first place, already owning a New F-1. I do a fair amount of bird photography with a 600mm lens and 1.4X or 2X extender, where the difference should show up, but it really doesn't. Of course if the New F-1 had MLU it would be even better than it is, but even without it, it's steadier than an EF or an old F-1 with MLU.