Originally posted by NeverSatisfied I tried the Kenko 1.5 TC, but it wouldn't do a thing when I used it with the DA*50-135. Couldn't seem to communicate with the camera at all. Althought I've heard other people say the Kenko HAS worked for them, so maybe mine was defective. I sent it back and bought the Tamron 1.4 TC, which works pretty well on the DA*50-135, and on my Tamron 70-200/2.8 as well. Even the Tamron's not 100% on the DA*, sometimes it's pretty slow to lock focus. It seems to work more reliably on the Tamron lens. Image quality on either lens is pretty good. I'm really looking forward to the new TC that Pentax is supposed to come out with, hopefully it will give even better AF performance.
By the way, some people claim that they are the exact same TC, just re-branded, but having owned both the Kenko and Tamron, they are NOT the same.
Hmm can you confirm which version of Kenko 1.5x you have?
1.Kenko DG Pz-AF 1.5x TELEPLUS MC
2.Kenko Pz-AF 1.5x TELEPLUS SHQ
If I am correct you have the MC (1) version
Daniel