Notorious T.O.D. wrote:
Yes, if you have the 70-200 f/2.8 IS II you can use the gen III Canon TCs with it. I have used the 2.0x TC III with mine and I can get out to 400mm that way. The 2.0 TC III is tons cheaper than the 100-400 II but people will argue the sharpness probably and the convenience factor...
Best,
Todd Ferguson