Helios-44M

Hi all I picked up a mint HELIOS-44M 2/58. here is my question. M42 mount? It will not thread onto my Pentax K-M42 adapter. It will thread onto a M42 body but not the adapter?

Maybe that lens thread is for T-mount? Try it on a T-mount adapter.

The lens will thread onto an M42 body I have sitting on my desk. When I try the Pentax adapter it only goes on about 2 turns and stops.

Is the auto diaphragm pin on the bottom of the lens catching in part of the adapter? Perhaps in one of the cut outs that the removal tool fits into- it has happened to me- or possibly the thread of the adapter is damaged. I have 3 Infinity m42-k adapters and all work with every m42 lens I have, including the Helios 44-m

Samsung GX-10,too many Russian Lenses, A lot of Zenits, an Almaz 103 a few Yashica,and finally a Minox35GT

well all my Pentax lenses work no problem. I have a couple of 3rd party lenses that work fine in the adapter also. Just not the Helios for some reason. The Helios works fine on 2 other M42 bodies. Must be the Pentax adapter has a real close tolerance. That's the only thing I can think of.