Does anyone know if there is one brand or type of teleconverter that works with both Canon and Sigma (DC & DG) lenses (prime & zoom)? Does Canon (II &/or III) work with Sigma? Do Sigma teleconverters work with Canon lenses? Does Kenko Pro 300 (DG &/or DGX) work with both Canon and Sigma lenses? Lenses being say between f-stop 1.8 and 4.0 to maintain auto focus.

Any info would be appreciated.

Thanks much!!