Thanks for the information... Yes, it is a Canon TC and I had a "Senior Moment" on the 70-200 issue... What I shoul have written in is the 100-400. As I gain more knowledge I am not so sure that taking the 100-400 and screwing on a TC might not be presenting a lot of variables in AF... maybe a bit too many. We'll see what happens... it should be interesting. Just ordered the FoCal Pro so I'm sure I will be back on asking more questions.
Bill