Quote Originally Posted by doggiedoc
That sounded like a reasonable idea, but what you guys are saying about loss of IQ with the extenders, I'd rather save up and own both lenses. =)

Good plan. The 70-200 II does pretty well with the 1.4x extender - my 70-200 II+1.4x is a tiny bit softer at 280mm wide open (f/4) than the 100-400mm at 280mm wide open (f/5.6); stopping them down to f/8 at 280mm, the 70-200 II+1.4x is a little sharper than the 100-400mm. But with the 2x, results would not be nearly as close.


Depending on your time frame, though, it might be worth seeing how the MkIII version of the 2x performs. It's due out soon, and I'm sure Bryan will test it with the 70-200 II. I really doubt it will equal the performance of the 100-400mm @ 400mm, but I wouldn't mind being pleasantly surprised! If it does well, a weather-sealed 140-400mm f/5.6 with 4-stop IS would be pretty sweet!