Trick to adapt mf lens

SmokingRibs · Joined: 03 Dec 2016 Posts: 2

Hi all,
First post here.

Here is my little problem. I have an Exactar 35mm f2.8 (http://allphotolenses.com/public/files/img/eb739c89cb602ba164e2b5560dcfa50e.jpg). I use a m42 to EOS adapter to use it on my Canon 6D.

In all other MF lenses I have (Takumar and such), when you screw the adapter the pin enter all the way. Then when you change the apparatus manually, the iris close down.

On my Exactar, when the adapter is screwed in, the pin is pushed, by I can't go beyond f8. I can still turn the apparatus ring, but the iris no longer close.

When I remove the adapter and put my apparatus to f22. Then when I push the pin, the iris close down as it should.

It feels like the pin needs a punch to close really small, not to being pushed down a priori.

Have anyone ever got that problem? How did you solve it?

I was initially thinking of gluing down the pin, but it wouldn't work, since it needs the punch above f8.

Thanks.

marcusBMG · Joined: 07 Dec 2012 Posts: 1304 Location: Conwy N Wales

This may be an option:

http://www.pentaxforums.com/accessoryreviews/kipon-m42-pk-adapter.html

DConvert · Joined: 12 Jun 2010 Posts: 902 Location: Essex UK

It sounds like your adapter is not pushing the pin in far enough for the lens. Try simply wedging the pin fully in before fitting it.

SmokingRibs · Joined: 03 Dec 2016 Posts: 2

Koen Nhz · Joined: 07 Jul 2011 Posts: 84 Location: Antwerp, Belgium

There is probably some oil on the blades so they need some speed to overcome the friction, in that case the only real remedy is to open up the lens and clean the blades.
In warmer conditions oil is usually less sticky so that might be a temporary solution to open en close them repeatedly for some time to get them loosened a bit.

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

cut a disk/donut from a plastic food lid, and shim between the adapters flange the the pin is to press against, you may have to experiment to get the right thickness.

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

If you are up to removing the mounting ring at the rear of the lens then make a small spacer from the end of a Ballpoint pen refill tube.
About 3mm-4mm should do it.Slip it over the pin and put the pin back in place.Some people find this stage difficult but a small magnet held over the pin whilst putting the ring/cover back in place otherwise it will just drop out.Otherwise,put ring upside down on benche/table and place the lens on top,I found that method a bit fiddly.

woodrim · Joined: 14 Jan 2010 Posts: 4060 Location: Charleston

Don't stop down past f/8.

cooltouch · Joined: 15 Jan 2009 Posts: 9097 Location: Houston, Texas

Your lens needs servicing.