Originally posted by GLXLR I think that the Full frame compatibility shouldn't be a factor (considering the huge price gap). I suggest go for the 70mm and spend the extra money on another lens!
Price gap = $164 USD...
Full frame compatibility is not really much of a factor unless you shoot film as well as digital. If I remember correctly, the OP (lawsonstone) has a fair number of film cameras.
Steve
(Really like the way my 77/1.8 looks on my older film bodies...still waiting for the first film pics...)