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Differences in M42 Mount
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PostPosted: Fri Apr 12, 2013 6:09 am    Post subject: Differences in M42 Mount Reply with quote

I recently noticed this difference in pentax M42 vs russian m42 mount,may be there is also other differences in lenses from different manufaturers,if anyone hasas any info please share here


PostPosted: Fri Apr 12, 2013 7:36 am    Post subject: Re: Diffrences in M42 Mount Reply with quote

raay04 wrote:
I recently noticed this difference in pentax M42 vs russian m42 mount,may be there is also other differences in lenses from different manufaturers,if anyone hasas any info please share here

There are quite a few variations between different manufacturers' M42 mounts. For example, Pentax Super-Multi-Coated and SMC Takumars had an extra lug on the mount to enable the transmission of aperture information into the camera, and a tiny pin to detect whether the lens was mounted on a compatible body.

Mamiya SX lenses had a lug and a "skirt", the later making SX lenses particularly difficult to mount on other cameras and today's M42 adapters.

EBC Fujinon series again had an aperture transmission lug in yet another place (special M42 adapters exist to accomodate those on digital; some owners butcher their lenses to fit - by filing the lug. I'm not one of them, but I owned a couple lenses "modified" this way).

Rollei also made lenses in M42 mount; they had yet another implementation of aperture transmission mechanism.

Some Russian lenses (e.g. Kaleinar-5H) came with interchangeable M42 mounts that would not fit onto a regular M42 adapter due to protruding part (the part is a Nikon Ai lug; special adapters exist to accomodate those lenses).

Some West German lenses (e.g. Schacht) have stop-down pins that won't go in completely, making the use of M42 adapters with stop-down flange impossible.

Certain lenses made for early Edixa cameras had their stop-down pin located differently on the mount, making the pin useless on other brand cameras.

I'm pretty sure there are other variations of this popular mount which may or may not be compatible with other M42 cameras.


PostPosted: Fri Apr 12, 2013 8:24 am    Post subject: Reply with quote

If you read the Evolution section of the M42 mount Wiki page, it will explain the differences in your pic. The Super-Tak on the left is an "auto" type, with the standard pin which is pushed by a bar inside the camera mount to close the diaphragm. The Helios is an earlier design, either a plain manual stop-down type or maybe a preset, I can't tell from the picture.

The Pentax M42 lenses followed the standard created by the German manufacturers, until they developed their own method of transmitting aperture information to the camera. The Russian lenses generally developed more slowly and lagged behind design advances, and stop-down and preset versions were continued to be manufactured well after the German & Japanese lenses had moved on. There are some exceptions to this, as always.


PostPosted: Fri Apr 12, 2013 9:48 am    Post subject: Reply with quote

The helios lens has auto aperture but the aperture pin is kept down using a rubber bush to make it manual aperture!!!

Would have been grt if someone can post or links to different m42 mount variations
Anyway thanks for the info


Last edited by raay04 on Sat Apr 13, 2013 5:27 am; edited 1 time in total


PostPosted: Fri Apr 12, 2013 9:54 am    Post subject: Reply with quote

Also some M42 enlarger lenses are quite anoying to mount on standart M42 adapters (longer treat pitch, protuberant things).

For exemple, this Vega 5u :



Also the Meteor 5-1 (I think made for K-3 videocamera) has this problem (+very long treat pitch)


PostPosted: Fri Apr 12, 2013 3:27 pm    Post subject: Reply with quote

My Helios 44m is odd as it will screw into an M42 adapter and into Praktica MT3\MTL5 but not into a Pentax....all my other screw lenses of different makes have no problem with the Pentax.


PostPosted: Sat Apr 13, 2013 4:10 am    Post subject: Reply with quote

Glad I ran into this post! I was just seeing this same thing when comparing my pentax taks against my Spiratone 28 f/2 and my jupiter 21m...

Thanks for the link too! Great reading!