Does all the teleconverters (Pentax and non-Pentax) do auto focus? If no, which of the teleconverters do the auto focusing. I mean, while attaching a manual focus lens, I heard that some TC does AF for the MF lens. Which of the TC does it? Thanks
The pentax 1.7 changes a manual focus lens to an autofocus (to a degree) lens.
There are other teleconverters which allow you to let an autofocus lens continue to be an autofocus lens. What works depends on which autofocus lens you want to teleconvert, but in general the sigma/tamron teleconverters do work.
Making an SDM lens continue to autofocus is slightlly more difficult and you gotta specifically check.