Does this beastie work best with internal 1.4 plus extra 1.4TC or better just a 2xIII TC? Would like to hear you experiences on that. I guess the 2X should be better but since the 1.4TC built in is so darn good...?
I have not done a huge amount of testing of this. Rigth when I got the lens I did take these testshot. Mounted on tripod. Shot at 200 & 400 mm without any extenders on, with internal on, with external 1.4 and with external 2x. Look at focal length then you should be able to tell what the combination was on each photo.