SDM focus does nto work with tele converter

Just been reading the topic on extension tubes and wonder if something similar would explain the issue I am having.

I picked up a tele converter... it has all the contacts including the two inside the lens for autozoom/SDM. With a continuity tester I verified that the contacts are functional from front to back.

Yet with SDM lenses, the camera goes right into manual focus mode. If I cover the two internal contacts the camera goes into a sort of error state and the screw drive focusing won't function either. So "some" sort of communication is going through.

Is there actually some sort of circuitry inside the lens that would need to know about the SDM protocol of some sort???

I was told that older teleconverters simply don't know how to make SDM work, but I would think the contacts would merely be a simple pass through.

Any ideas? Is it possible to make my DA* lenses autofocus with the teleconverter?

Thanks!

Which model of tele converter is it?

AFAIK the 2 contacts inside the body provide only power, either for the SDM electronics or power zoom on suitably equipped lenses.

My 1.4x (think it's Tamron) converter works just fine with SDM, so not sure what's going on there?

The tele-converter is a Tamron 2x pz-af mc7.
I'll have to look at the other contacts.

If the two internal contact are only for power, then Perhaps something is missing. But all seven contacts are there,the A* lens has six.
Hmm, one of them seems to be indented further than the rest.
I'll have to see if that might not be connecting.

Although I went to the camera shop, and they had another brand, also with all contacts. It also failed to function. There must be something about the older v.s. newer tele-converters that are required to suport SDM focusing. Bummer...

I have a Tamron converter, I discussed it a while back on this forum. It also did the same thing, however when I put the converter and lens on my MZ5n it worked on screw focus! I ended up getting a Kenro 1.4 conveter - works a treat! I never did find out what the problem was. I also tested the circuit!

Mine is the same as Mike's in the for sale section.