M42 Lens on K10D.


Link Posted 23/05/2011 - 11:29
Any Information appreciated.

I have a K10D, and would like to try a number of prime manual lens, from my Pentax film SLR, (M42), I already have the Pentax K mount to M42 adaptor. I know I will have to manually compensate for exposure as there will not be any feed back to the camera, as to aperture settings etc.
My concern is, as there will be no connection to any of the contacts on the camera, that normally connect to auto lens, will this cause any damage to the electronics within the camera, as all these circuits will be open.

Many thanks.

Chris R.
Chris R.

I. El. (Eng). (Rtd).


Link Posted 23/05/2011 - 12:06
No, it will be fine. In fact the metal base of the lens is supposed to short out some of the contacts, if this doesn't happen you won't be able to enable 'catch-in-focus', among other things. Some M42 lenses have black painted bases (e.g. Takumars), you will need to either scrape a bit of the black paint off to expose the metal, or paint some metallic paint over the bit where the contacts touch, or stick a piece of aluminium foil on there.

Some M42 lenses have every narrow bases, and will miss the contacts entirely (I've had a Pentacon 135mm which missed the contacts completely, and the Super Tak 50/1.4 only barely touches the contacts). Not a lot you can do in these instances, one of those M42/PK adapters with the flange might help but you will lose infinity focus.

Here's a photo showing a bit of a frakenstein, an Adaptall-2 lens with M42 mount (it was the only mount I had at the time), with a M42/PK adapter attached. You can see the tin foil which shorts the camera contacts to enable 'catch-in-focus'.

Tamron Adaptall 2 80-210 f3.8-4 by thoughton, on Flickr
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
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Last Edited by thoughton on 23/05/2011 - 12:13


Link Posted 23/05/2011 - 19:45
Many thanks, Tim.
Chris R.

I. El. (Eng). (Rtd).


Link Posted 23/05/2011 - 22:06
Use copper tape if you don't want to damage the paintwork. Careful is is so sharp and hurts like mad when you cut yourself.



Link Posted 24/05/2011 - 08:45
Many thanks, Dan.

Yes I know how sharp metal tapes can be. I was an industrial electrical engineer, all of my working life, (now retired), but I know zero, re electronics, hence my original question about the open circuit contacts.

Getting it wrong, when I was working, was not really an option, but if things did go wrong, there was one hell of a bang, a lot of embarrassment, plus an enquiry.

But what I do know of electronics, if you get it wrong, there is just a silent fry.
No work no more, scrap bin.

All the best.

Chris R.
Chris R.

I. El. (Eng). (Rtd).
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