Please help: Minolta MD 50/1.7 re-assembly

Amamba · Joined: 13 Jun 2013 Posts: 15 Location: SE MI

I took the mount off to clean inside. I was foolish enough to let the aperture ring lift just enough for the small ball that makes it "click" in place to get lost.

Now, I know that I can use a regular ballpen ball instead; the problem is , I just can't seem to find the correct position in which the mount should be to properly set it. I either get the aperture ring locked in place, or unable to close all the way down. I took some other Minolta lenses apart before, but this one seems to be very finicky regarding the assembly method. I did try to find references online but my google foo wasn't sufficient.

If you can point me to assembly instruction for this particular lens, it would help tremendously ! Thanks in advance !

parabellumfoto · Joined: 06 Apr 2013 Posts: 413 Location: Sydney, Australia

There are little grooves that the little bearing rolls over. This is what makes the aperture 'click.' When you find these grooves you will know where to put the bearing in the aperture ring before replacing back onto the lens.

First off just put the aperture ring back on a few times so you know how it goes back on correctly. F1.7 is the widest aperture so make sure it corresponds! After you do all that and you a sure about correct position and installation, slot the bearing into the little pocket on the aperture ring is and put it back together.

I lost my bearing but was lucky enough to find it again and put it back.

Hope all this makes sense.

koji · Expire: 2012-12-27

Does it help?

http://www.pbase.com/kkawakami/image/97684957

This lens is MC ROKKOR-PF 58/1.4, so do not expect the same as yours,
but you can find its hole at the similar place. Just check the inside of
your aperture ring, there must be 5 or 6 engraved lines for click stops.
So you can guess its hole position at where those lines meet the lens body.

parabellumfoto · Joined: 06 Apr 2013 Posts: 413 Location: Sydney, Australia

Amamba · Joined: 13 Jun 2013 Posts: 15 Location: SE MI

OK, thanks for all the replies.

The photo doesn't quite help. The ball bearing "seat" (a tiny metal tube) is on the aperture ring, and there's a number of grooves on the body of the lens. The problem is finding the right groove and the right position of the aperture ring. Somehow when I try to put it all together, one of the three things happen... either the aperture ring ends up in a wrong place, i.e. when I align the screw holes on the barrel with the holes in the mount, the aperture wouldn't close fully; or, if I try to place the ball in the rightmost groove on the barrel (looking with barrel down) the aperture ring locks up and wouldn't move at all.

I can re-assemble it without the ball, but the aperture ring then just floats.

I had before successfully re-assembled a MD zoom, but it had a different and simpler arrangement.

I will try and post photos of this lens, hopefully this would make it easier to ID the problem ! I have another 50 /1.7 but I gave it to a friend.

parabellumfoto · Joined: 06 Apr 2013 Posts: 413 Location: Sydney, Australia

Amamba · Joined: 13 Jun 2013 Posts: 15 Location: SE MI

Thanks for help !

Well... I broke it Twisted Evil

Or, perhaps it was broken right from the start, which may explain why it would lock up with ball inserted. Anyway, as I tried to undo it again, the little spring loaded tube that pushes the ball got pulled out & deformed.

So, now I have a lens with continuously variable aperture.. how cool is that ? Laughing

No more adjusting aperture in finite increments ! It's a complete freedom, baby ! Of course the downside is, it won't stay at selected aperture if you as much as bump the ring.

Luckily, I have another one.