Teleconverter for K20D

Hi All,

I’d like to experiment with a teleconverter/rear converter for my K20D but I’m getting increasingly confused as to what I should buy.

I’ve read lots of forum posts and guides/reviews but I guess my main problem is a lack of understanding regarding lens mounts and a lack of understanding when reading technical information about lens.

For example, I’m rather confident the Pentax 2X-S would be fine on my K20D but what about a Teleplus Pz-AF 2X MC7. The Teleplus apparently has “a Pentax mount” but that could mean anything (K or M42?).

Also, there a lots of very cheap teleconverter on eBay which seem unbranded , e.g. “Pentax K teleconverter”.

Some of these cheap teleconverters also that claim to include autofocus, but I thought AF was unavailable in teleconverters (unless you spend a lot of money on something special).

So, as you can see, I’d like to buy a teleconverter but I’m confused as to where to start looking and what to believe.

Could anyone recommend a teleconverter for a novice photographer?

Many thanks,
M.