Pentacon-B Prakticar 50/2.4 -- bashed focus ring

RioRico

What's up: a Pentacon Prakticar 50/2.4 in Pentacon-B mount, #3149835, made by Meyer according to [ http://praktica.planetaclix.pt/lenses.html ]

So I got this baby REAL cheap because it was sold for parts -- some internal wires are broken, but the main problem is the focus ring. It is dented so that it jams against the objective body. It still focuses, but is VERY stiff. I've tried my usual trick involving screwdrivers, pliers, hammer etc, but I can't force-out the dent. The focus ring probably needs to be removed -- but how?

And my next question: Is it worth attempting? Is this just a thin Domiplan?

Minolfan · Joined: 30 Dec 2008 Posts: 3437 Location: Netherlands

It is not a triplet like the Domiplan but a four lenses construction: http://forum.mflenses.com/prakticar-2-4-50-and-extension-tubes-t26052,highlight,prakticar,start,15.html
Koji has some samples on Pbase: http://www.pbase.com/kkawakami/prakticar_50mm_f24
But I think it is easier to find a better one for cheap, than repairing the dented one.

RioRico · Posted: Wed Mar 16, 2011 6:35 pm Post subject:

Ah, so it is an Ernostar design. That is interesting, historically. But I probably won't buy a better one, mainly because, as I find now, the PB-mount register (44.4mm) is too short for a Pentax mount (45.46). Also because I am cheap. If I could disassemble the lens, I *might* be able to rig an M42 or PK adaptation. But I don't know where to start, taking it apart.

trifox · Expire: 2014-05-29

Rio -- you need a rubber ring i.e. sink plug - it's cheap and enough ..

The best way how to get to the helicoid (well, if the problem is there ) is take the front retaining ring out

and you can see inside quite well ...

I am preparing a few pictures ..

hold the line Wink

trifox · Expire: 2014-05-29

1 - TAKING APART

2 - PUTTING TOGETHER

RioRico · Posted: Thu Mar 17, 2011 4:38 am Post subject:

WOW! Excellent!! Thankyou thankyou! I'll get a sink plug tomorrow and try this out.

mo · Expire: 2016-07-30

Stan you make it look too easy.. Laughing

Minolfan · Joined: 30 Dec 2008 Posts: 3437 Location: Netherlands

Well, I really get tempted. In my drawer is still a Jena Prakticar 50/1.8 (Pancolar) with the same problem. I''ll have to take it out of its hiding place and give it a try. Changing the mount to M42 would be a fine option too.
Let us know if you succeed!

trifox · Expire: 2014-05-29

mo - this one is easy Cool

each lens has own - tips-and-tricks but sometimes -- especially with cheaper lenses -- oh my god! one has to be careful.

The biggest problem are fasteners or screw they're totally stiff

extremely high attention and care needs to be considered and WD-40 (or any penetrating oil) always on hand ..

Another big problem is screws there not replaceable because they're not common (i.e. japanese industry standard) once that screw is damaged, it's really hard to find replacement one or takes a time at least.

tf