Today I discovered all m42 mount lenses arn't the same are there two types ?

BADGER.BRAD

BADGER.BRAD

Messages
3,670
Edit My Images
Yes
Right under the banner you learn something new every day. I sneaked the newly acquired Praktica to Bridgenorth ( local Market town) on a charity shop shopping trip for possible steam Punk outfits and thought I'll put the Helios M42 mount lens on, on first shot I realized the camera was jammed ! As I have only took a couple of shots with it with another lens on I thought the camera was shot but when I got home I realized the Helios was jamming the mirror from moving as it goes too far into the body. Is there two types of M42 mount Lens ? I will need a new second hand lens so wish to make sure it will fit. Here are a few pics.

Original lens top Helios Bottom

41113674411_08d40a66af_k.jpg

Pentacon 135 at the top which fits ok and Helios 58mm at the bottom, the flange beyond the thread jams the mech

39305131930_b7ba50f005_z.jpg

The standard lens has a flange beyond the thread but it is tapered as per top photo.
 
That is a Auto aperture Helios. Can see the button and the AM switch on side. That barrel does seem to come back a lot further than I recall. Will pull an old preset and an auto out to look.

Edit - Both my Helios lenses project as far back as that, when focussed at infinity, so must be an extra long mirror on the Praktica - so il learned something new too
 
Last edited:
The Helios 44 2/58 lens came as far as I know with the Zenit TTL my dad owned and then he brought a 35mm and a 135mm Pentacon lenses, He changed to Praktica I'm guessing at the point the Zenits mirror mech died which is how I found it in his collection. All the Prakticas I have use Praktica bayonet fitting. I have used all the M42 lenses but on a DSLR with an adapter which never caused any probs so of course I never noticed any difference. As I will most likely source a new lens from ebay how do I know if it will fit ?
 
The mirror in Praktica (and many other makes) cameras is bonded to its base with glue. This glue can soften and over time the mirror will move slightly downhill and foul the rear of the lens. The cure is to slightly warm the mirror and push it back uphill.

There is no intended versions of M42 lenses - all lenses should fit all cameras but there are variations. For example Edixa lenses have longer than usual aperture pins and most M42 lenses will not work correctly on Edixa cameras. I have never tried an Edixa lens on a non-Edixa camera but I can imagine that longer pin causing problems.

The Helios lens should work fine on a Praktica - my Helios 44 and Helios 44M certainly work well on my M42 Prakticas.
 
Last edited:
Here another example showing the difference:

Pentacon MC 28mm f/2.8 (left)
Carl Zeiss Jena 50mm f/2.8 (center)
Asahi Super-Takumar 55mm f/1.8 (right)



The CZJ has a larger flange, that makes impossible for me to use the lens with e.g. a Cosina Hi-Lite EC body or with an adapter for C/Y mount.
 
@john.margetts - Interesting about the mirror slip - will take a look at my Prakticas. I do have one 'M42' lens that will not fit my other M42 cameras and that is a Mamiya SX one (for Mamyia MSX/DSX) - it has an extra pin and ridge for allowing full aperture metering that fouls normal M42 bodies. There were also I recall some problems with M42 auto aperture lenses on bodies that had screw holes in unfortunate places that the pin went into (My old Zenit B body was one that had a problem with that, had to use a feeler gauge to lift pin and then filled in the screw head with epoxy). Some SMC Tacumars also had extra pins and bumps on back for some reason.
 
I can remember at least 3 variations on the aperture control system on the M42 lenses I used to use. The most basic had 2 rings, 1 that you set as a stop for the other which you wound fully open to focus then turned to the pre-set "stop" you had selected with the 1st ring to shoot (or preview DoF). The next had one ring and a lever; you set the shooting aperture with the ring, pressed the lever down to open up fully for focussing then as part of the shutter release action, the camera pressed the pin which released the lever allowing the iris to close to the pre-set aperture. The easiest one to use was the one that had a single ring and was just stopped down by the pin as the shutter went off.

Looking at Ariel's photo of the 3 lenses, the middle one looks more like an M39 thread.
 
Nod said:
...Looking at Ariel's photo of the 3 lenses, the middle one looks more like an M39 thread.
Click to expand...

It is a M42x1 (1 mm thread pitch) from a Praktica FX, it is a small body lens maybe that is why looks like a smaller thread compared with the other two.



What I do not know are the names or denominations for the different flange sizes, because the diameter and thread pitch are always the same (at least in all the M42 lenses I have).
 
Sorry for the error, I was using the highly scientific method of measuring the relative sizes of the mounting threads and the middle one is narrower than the 2 outside ones (using that method of measurement!)
 
Nod said:
Sorry for the error, I was using the highly scientific method of measuring the relative sizes of the mounting threads and the middle one is narrower than the 2 outside ones (using that method of measurement!)
Click to expand...
Pincushion lens distortion ? :cool:
 
You must log in or register to reply here.
Back
Top