I'm looking at extending the reach of my longer Nikon-mount lenses and am wondering what will give best results? Options I'm considering, by price: Nikon TC-14B (~£100, reasonable by modern standards) Sigma APO 1.4x EX (~£125, for film, presumed better than TC-14B) Sigma APO 1.4x EX DG (~£165, for digital, not quite as sharp as TC-14E) Nikon TC-14E (~£200, very good optics though may have to grind off metal tab to fit MF/early AF lenses?) Sigma TC-1401 (~£210, slightly sharper in center than TC-14E - where it counts) Olympus MC-14 (~£230, no clearance issues once NF-µ43 adapter fitted) There's very little in price between the modern optics, and as much as I'd like a bargain I suspect I'd just be disappointed with the old film lenses. I suppose really the choice is between the newest Sigma and the Oly. I've read various complaints about mixing Sigma and Nikon lenses/TCs but this always concerns AF which is of no concern to me. Perhaps swinging in the Oly's favour is the lack of clearance problems with SLR lenses which makes it most adaptable for some curious combinations (plus I could use it with Oly's Pro lenses if I ever have a couple of spare grand - unlikely!). My largest concern is with it being so specifically designed with just two lenses in mind, how will it perform with random vintage glass designed for film plonked in front of it? Advice welcomed!