I am trying to get a Teleconverter to suit a Pentax KAF mount. I am not fussed if it is a 1.4x 1.7x or 2x anymore as anything is better than nothing. But I do want a quality one.
Idealy Tamron or Pentax
There are lots of aftermarket ones available, but I prefer a quality brand, but they seem to be discontinued. Sigma unfortunately has some compatability issues.