Comments about Sigma Sigma 2x EX DG APO Tele-Converter AF for Pentax AF Cameras:

I made the decision to purchase after satisfying results with its little brother, the 1.4x EXDG. I was rather surprised and disappointed at the performance of this version. While I expected some image degradation, the very high IQ of the K20D plus some sharpening in Lightroom should have compensated, IMO, but it did not.

Comments about Sigma Sigma 2x EX DG APO Tele-Converter AF for Pentax AF Cameras:

I bought this to use with a Sigma 70-200mm f/2.8 EX DG HSM (and a few other initials I forget). After much testing and no acceptable results, I found a page on the Sigma Japanese site that says that it is not compatible with my lens, but is with the non-HSM version - I hadn't checked the initials on the lens compatibility list close enough. It may be a fine product, but it confused my camera's light sensor and didn't fit any of my other lenses, so I returned it.