The EDIF f/4.5 and f/2.8 should produce much better images that the f/4 especially in manual focus. These two lens produced most of the wonderful images you grew up enjoying National Geographic back before lightroom and photoshop when all you had to work with was the light hitting the film. The TC-200 will work well on the f/4.5 and TC-14B on both. I don't like the TC-300 as mikew said, it is better to crop than use that. I've tried the TC300 on the 300mm f/4.5, f2.8 and the 400mm f/3.5 (all much sharper than the 300mm f/4) it is a waste of time unless you need the extra boost on live image for a distant shot.