[geoffox23]

I have recently purchased an "as new" Tamron TC, and I have noticed a varying degree of resistance in the focus ring when using my AF lenses set to MF with the teleconverter fitted.

FA50.. slight resistance but still able to be focussed accurately.
F35-105.. slight resistance but still silky smooth.
sigma 18-125.. feels crunchy, only able to focus in small increments.
sigma 17-70.. not quite as crunchy as 18-125 and able to focus in small increments
sigma 10-20.. same as 17-70
sigma 135-400.. very stiff, difficult to focus in small steps
tamron 90.. similar feel to FA50

I got these results with the lenses straight from the bag, not attached to my K100D.

I have no previous experience with a AF teleconverter, and wonder if others with this TC can produce a similar result.

Geoff