Bill,

That's correct. On a 7D and all non-1D cameras you can only add a 1.4 tc if
your lens is an f4 or bigger aperture. To add a 2.0 tc you need a 2.8
aperture or bigger for auto focus.


Bill Anderson wrote -----> Today ?I was at Kenmore Camera asking about
teleconverters.?? The person at
Kenmore told me that the maximum?aperature for auto focus to work is 4.0 or
4.5
(I forget which), which is why I did not buy one to couple with my? 7D +
100-400
zoom, which?has a maximum aperature of 5.6 at the 400mm setting. <---

Doug Schurman
Seattle, Olympic Hills Area