Canon 70/300 L f/4-5.6 & Kenko Pro 300 1.4X TC Reikan FoCal... Several Questions

[ChadS]

I'll trade ya a 70-200 f/4 IS for your 70-200 IS f/2.8 - that'll save you some weight... !

I don't think the hunting has anything to do with AFMA. That's just a consequence of using an extender on a lens as I understand it. Some work better than others. The Gen 3 apparently work really well with the new super telephotos (and the 70-200 IS f/2.8 II) but not so well with older lenses - both in terms of IQ and AF speed. This makes sense as the camera is expecting a certain profile from the lens and not getting it - not to mention isn't got a slower f/# to focus on (the faster the f/# the more you can tell you're drifting out of focus).