Multiplier not Autofocussing

I have a Kenko P-AF 1.4x MC4 multiplier that has developed a bizarre problem when paired with my DA*16-50. It simply will not auto-focus - the camera display rapidly 'flickers' between MF & AF but the lens will not autofocus. I have tried cleaning the contacts on both the lens and the multiplier but the problem still occurs.

However, when I use it with any other of my fast lenses it works fine, i.e. it auto-focuses in whichever mode I have selected.

Any suggestions/thoughts?

Phil

I have never got any teleconverter, bar the Pentax 1.4x WR, to autofocus reliably with SDM on Pentax bodies. I have the Kenko 1.5x and although it has the required contacts for SDM it hunts back and forward and rarely locks focus.

Interestingly it used to work a lot better until Pentax issued a firmware update (some time ago) when they released their own 1.4x WR converter.

Mike

Thanks for pointing me in the right direction. I've tried it with a couple of slower screw drive lenses and it works fine.

it's just not happy on the SDM ones.

Phil

Yes, doesn't work well with Sigma HSM either.

They won't play with the PLM 55-300 either.