pentacon MC 50mm 1.8 fix loose barrel

kiddo · Joined: 29 Jun 2018 Posts: 1275

Hi, I need help with this lens, the inside barrel is sort of loosened. So , maintaining the outer barrel by hand ,the inner one it's got a little play , the mount is M42 . I assume it shouldn't be a big deal,but after using the Helios the other day, I was going to take for a walk the pentacon and I don't like loosened things in the lenses.

alex ph · Joined: 16 Mar 2013 Posts: 1674

I have the same lens in Praktica mount, and it has the same issue.

The version I has is dismountable from the bottom. You need to take off the plastic "cover" from the mount (just carefully pushing it off) and to get reach to the retaining screws. Once you unscrew them and the mount is off, you'll have access to the inner ring where the attachments might be tightened without the further disassembly. In my case I could not get off the mount because one of the four screws found itself just dead fixed. I completely erased its head with a screwdriver, with no effect. But I could see the loosened connectors through the hole.

If the construction of your lens is the same, and your screws unscrew, you may fix the issue.

kiddo · Joined: 29 Jun 2018 Posts: 1275

Thanks for your answer. The M42 mount it's got 3 screws on the mount, I've never taken out one yet, is it safe to remove the mount by unscrewing those 3 screws? In nikkor I've had no troubles , but Canon nFD was a pain in the.....to put it3 back

kiddo · Joined: 29 Jun 2018 Posts: 1275

The mount is all metal,no plastic cover at all, at least on the outside....

Eddie46 · Joined: 05 Dec 2016 Posts: 135 Location: cardiff,UK

This should help. Although this is the Early model,a rebadged meyer Optik.
https://www.youtube.com/watch?v=I-06BGrA6Bo

alex ph · Joined: 16 Mar 2013 Posts: 1674

A very instructive video, Eddie, thank you!

Kiddo, from your words and from the above video I conclude that mechanically the Prakticar version is a completely different lens. But the M42 version seems easier to dis- and reassemble. Good luck with your reparation!

kiddo · Joined: 29 Jun 2018 Posts: 1275

Thanks for the video, I've opened it up, and when I've got up to the inner side ring which sits on top of the blades, there weren't the 3 screws to remove that ring, only 3 centers which helps the ring to sit on top of the 3 bolts, so I asume that ring it's been glued on top of the helical. I assume that the problem with the front group, might be underneath of the front Name ring ,so probably there are some screws underneath,but right now can't take it out.