Automatic macro extension tubes

I recently bought a set of old Aico automatic extension tubes for my k-r. I was expecting to be able to use the aperture control on the camera body, since the tubes have the mechanism to transmit the movement through them. However, the camera doesn't recognise the aperture setting when I put an auto lens on. There are no electrical contacts on the tubes. Are they an older format for purely mechanical aperture control? Is there any way to get the k-r body to actuate the aperture manually?

I have read about removing anodisation to make electrical contact, but a bit confused on this matter.

TIA

If the tubes do not have the electrical contacts then they won't provide any auto function

Take a look at the ones I have just sold - they have the contacts and the "modification" :
https://www.pentaxuser.com/forum/topic/fs--danubia-auto-extension-tube-set---pka...

If you're desperate I do have a Jessops set with the contacts that I'm no longer using.

Or you can buy these new, they have all the right contacts I believe:
http://www.harrisoncameras.co.uk/pd/Dorr-Extension-Tube-Set-122132mm-Pentax-KA-F...

Cheers

Ah well, thanks for the advice.

I picked them up for a fiver, so I've got a good quality solid set of tubes for the same price as a crappy set from China on eBay, so I can't complain.

Just got them to have a play really - I haven't done any macro photography before.

Cheers

Once you've got your exposure sorted out they'll do the same job. The quality of the air within the tubes doesn't vary much from type to type

If you want a good set of "tubes" that transmit data and action to an 'A' lens, get a Pentax 'A', f 1.7 50mm from that highly disparaged EBay place (dunno why people curse it so). Take all the glass out of it by carefully unscrewing each element. Get a reverse 49mm adapter (also from the never to be sufficiently damned place). While you're at it, get an old silver plastic fantastic Pentax AF 35 - 80 zoom.

Put the glassless 50mm on the camera. Screw the adapter on to the filter ring. Mount the AF backwards onto the adapter using its filter ring.
You now have a stunning (manual) variable focus macro lens with full aperture control that will go to about 5:1 - cost - about £20 - £30max.




On the other hand, you could always buy something very expensive?

Wow, nice thinking. I might try it if I want to get more serious about macro photography.

Agree about eBay - most of my cameras, lenses and gear (including above-mentioned set of macro tubes) have been from eBay.