Kenko 2X Converter for Pentax 67

I have recently acquired a used Kenko 2X teleconverter (Teleplus MC6)

for my P67 and I have some really stupid questions. I have never even

seen one in-person before much less used one. It seems to be in

really good condition. I put it on the camera with my 200/4 lens just

to check it out. There is something that I noticed. The mechanism

that actuates the auto diaphragm seems loose. It just "flops" when

you pick-up the converter. Is it supposed to be spring-loaded? (I

told you that my questions were stupid!) Or does it simply work in

conjunction with the actuating tab on the lens that IS spring-loaded?

With the converter installed, my TTL metering does not seem to work.

Any suggestions would be appreciated. I thought that I got a pretty

decent deal on it ($200). Now I'm not sure. Also, will this unit work

with all P67 lenses? Thanks in advance!

I have the same combo. The diaphram does 'flop' when it is off the camera, but not when it is on the camera body.

Mine works fine with the TTL, just make sure the lens is on 'auto'.

It will not work with very large 67 lenses, longer than 400mm anyway (my understanding).

You paid about what I did, frankly I've never been crazy with the optical performance of mine, but then it maybe my technique; 2X TC + 200mm lens is an awfully long beast not to have a tripod mount for.

Both my Teleplus MC6 extender and the set of Pentax auto extension tubes 'flop' when not fixed in camera. There seem to be a spring inside, but very weak. But in use, no problems. TTL metering works as well.

I bought my extender in Japan and paid 15 000 yen for it (about USD 120). It is a user, optically flawless but with some big scratches on the outside. So 200 should be okay price for a 'mint' example. I would not use it with a wide angle, but it works well with my 135 macro and 300 IFED.