MD mount problem

secludedsea · Joined: 01 Oct 2014 Posts: 82 Location: Adelaide, Australia

I've been lurking for a wee bit, but have just run into a head scratching problem that has caused me to register and ask a question!
I have a variety of MF lenses for my Olympus EPM1. Some of them are MD mount and I have a few MD mount adapters. My priblem is that I have at least three of these lenses where the aperture blades do not move when I use the manual aperture ring. In one case they stop down when I move the blade on the mount, but for the two other MD lenses, the pin does nothing at all. They are all in excellent condition and I find it odd that the iris does not work at all for two of them. The Tokina 28mm 2.8 is in great nick and has the two square tabs below the aperture ring, but the aperture blades just don't move at all no matter what I do. What am I doing wrong here? How do I actuate the blades? Am I supposed to do something to it to get it to work?

Steve

Layer-cake · Joined: 18 Mar 2013 Posts: 560 Location: Cape Town

I had a tonkina RMC 28mm that had stuck aperture blades, seems to be a common problem with this lens. was the first lens I ever fixed and not the easiest as I took the whole thing apart...no need for that to fix the blades it turned out.

what you can do to check if the blades are stuck is shift the aperture ring to its minimum size ie: F16 f22 and then move the pin at the bottom of the mount to see if the blades move.

if they don't then its most likely a case of stuck aperture blades and will needs clean.

the tokina is a very nice lens and well worth the effort to get up and running again, there are a couple of walk throughs for this lens, I'll try and see if I can find a link for you.

Layer-cake · Joined: 18 Mar 2013 Posts: 560 Location: Cape Town

heres one link but there more

http://m.youtube.com/watch?v=DdwvzJuuu-g

secludedsea · Joined: 01 Oct 2014 Posts: 82 Location: Adelaide, Australia

Thank you for that ! I've moved the aperture to the smallest setting of f22 and moved the pin on the mount. No stop down movement at all. I guess they're stuck! I'll look out for those walkthroughs and contact the seller in the meantime for at least a partial refubd. Not very happy Sad

In all other ways it's as clean as a whistle.

Steve

Tervueren · Expire: 2014-11-08

Send it back, the blades may even have been removed

Gardener · Joined: 22 Sep 2013 Posts: 950 Location: USA

Tervueren · Expire: 2014-11-08

secludedsea · Joined: 01 Oct 2014 Posts: 82 Location: Adelaide, Australia

I'll check today in the light. I guess it does happen, but I'd have to question why a seller with a perfect track record on ebay would even bother to do it? I contacted him and he assured me that it worked on his Nex before selling it on. Not sure I believe that unbless it had been sitting on a shelf for a long time and the oil stuck the blades tightly. Should I pay for postage, send it back and get a full refund or what? This lens is not going to be an easy fix, especially since I'm no engineer type!
To compensate, I did also receive a Pentax-M SMC 50mm 1.7 on the same day which looks in top condition and has beautiful blades and glass Smile

I'm also super happy with my Petri 55mm 1.8 lens. On a test run it looks to be super sharp with good colour at 2.8 and above. So, it's all swings and roundabouts with old lenses I guess.

Steve

Lightshow · Joined: 04 Nov 2011 Posts: 3669 Location: Calgary

My Rokkor MC 85/1.7's aperture went from snappy to sticking in 3 months, after I cleaned and lubed it, smooth and snappy.
I haven't come across any lensesmissing blades, very rare occurrence I'd think.
If I remember right, the aperture uses a spring to prevent damage should the blades stick.

secludedsea · Joined: 01 Oct 2014 Posts: 82 Location: Adelaide, Australia

Well, luckily the seller has offered a full refund and payment for postage back to him. I have a Rokkor 50mm 1.7 and I think there is a spring. I do have a question though. With these Rokkors where the mount pin stops down the iris, how does one stick it to the side in an adapter so that full manual control can be given to the aperture? I don't see anhy flanges or screws in any of my adapters to keep the mount pin in one position in order to have control of the blades. It puzzles me because I haven't come across this issue in any of my internet travels. Are folk just modifying the pin so as to maintain control of the iris, or is there a special MD adapter that has a stop screw for the pin?

Lightshow · Joined: 04 Nov 2011 Posts: 3669 Location: Calgary

This mount works the opposite, the lens should stop down when off the body, the camera holds the lens open till the moment just before picture is taken, the lens stops down on its own, then the camers opens it up again.
The little lever at the side of some lenses is for DOF preview, and overrides the camera.