Takumar A 2X tele-convertor

Posted a question about this in the troubleshooter forum, I'm not sure if the lack of any responses is due to fewer people browsing that section of the forum so I'll try here.

My latest ebay bargain? arrived today, a Takumar - A 2X Tele-converter.

I tried it on My Samsung GX 1S with a SMC Pentax-A 50mm f1.7 and it works fine however the same lens and teleconverter fitted to my Pentax K20d won't work properly - with the lens aperture ring on the 'A' setting it stops down to f22 and the viewfinder is very dark, I can get it to work by enabling use of the aperture ring in the camera menu and setting the apertures manually but don't understand why the 'A' setting doesn't work.

Any help would be gratefully received.

It's best to post in one place only. Lack of replies suggests nobody knows!

As an "A" lens it ought to work.

The usual cause of problems of this nature is dirty contacts. Give them a good clean (lenses and camera); make sure they depress and spring back properly, and try again.

G

George,

Thanks for the advice.

A problem with the contacts was my thought and the springs in a couple of them do seem weak - but the fact that it works on the Samsung seems to suggest they are fine.

I'll try giving them a good clean and see if it has any effect