which convertors?

FWIW, frankly I was never impressed with my copy of the 80-320: not very sharp or quick to focus on my old MZ-5N and no better (probably worse) on the GX-10/K10D that followed it - and it developed a terribly wobbly barrel which several reputable repairers refused to touch (no parts, even 8 yrs ago).

Therefore, on reflection, I would not want to put a T/C on it anyway..

Also, although my very early non-HD 55-300 is very sharp when used on the K-5 etc., when I tried it with the Kenko 1.4X on the GX10/K10D a few years ago, I was not very impressed with that combo either - but the T/C does seem to work reasonably well with the 18-135, and so I keep it for use with that on holidays when I need to keep the travelling weight down..

Geordie

I think we are talking somewhat at cross-purposes - what I was trying to say was that whilst the Pz version of the 1.4x Kenko does work with SDM (etc.) the Pz version of the 2X Kenko does not appear to from the reports I read, although I have never had one (and would probably never buy one as my experience with several 2X T/Cs was less than stellar - even Sigma's own one used on their lenses!).

I did not mean to imply that the Kenko 1.5X won't work - and, OTOH, the US reviews rated the 1.4X slightly better than the 1.5X.

Ok Bruce here are a couple of quick snaps of the contacts

Geordie

IIRC it's not just the number of contacts but also about the internal circuitry inside, and that the 2.0X is different to the 1.4X!

Sorry John, Bruce asked for a photo of the converter contacts this is what I have posted, once again it is a 1.5X not a 1,4 or 2X

Hi Geordie thanks for pisting.
I have went for the one from SRS X2 pz convertor called them up and they say AF etc works.
Years guarantee as well.

The Kenko 1,5x Teleplus MC DG is a very poor TC.
The Kenko 1,4x MC4 DGX (non-SMC) is actually one of the best you can buy. I'm not sure if the current model is identical.

SEE:
http://www.traumflieger.de/objektivtest/open_test/telekonverter/overview.php

I can't read German but Bruce might be able to translate any interesting points.

Zentrum = centre. What does erw. zentrum mean ?
Rand = edge

Note all 2x are poor. Most 1.7x are good from my experience.

--

I bought a Vivitar MC 2x PK-A/R-PK converter a while ago but it hasn't been used much as none of the auto functions worked despite being in pristine condition and having the contacts. Spurred by your thread I found the solution online, which is to scrape off some black coating where the 7th contact from the camera touches, as per the pencil tip in this photo:


Now the auto aperture functions work fine, it just needs manual focusing and input for shake reduction. These can be found quite cheaply and of course should be compatible with full frame (which the current 1.4x isn't).