Home

Please support mflenses.com if you need any graphic related work order it from us, click on above banner to order!

SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

About M42 lenses with A/M and pin
View previous topic :: View next topic  


PostPosted: Mon Nov 23, 2009 8:33 pm    Post subject: About M42 lenses with A/M and pin Reply with quote

I received my second lense which is Jena Tessar 2.8/50.

It has A/M switch and a pin at the back side. It is of course in the M mode but the aperture will not work. A friend warned that the pin must be somehow pressed for the aperture to work. Anyway I try to press the pin with my finger and try to move aperture ring and the aperture do not still change. Surprisingly it sometimes works (even the pin not pressed). What am I missing here?


PostPosted: Mon Nov 23, 2009 9:21 pm    Post subject: Reply with quote

Well I only know Myer, Helios and pentax but am sure the principle is the same........The pin is used when the lens is on auto, a lever in the camera body depresses it to the selected F-stop that you have chosen. If you have switched to manual the pin does nothing because the lens is already stopped down.


PostPosted: Mon Nov 23, 2009 9:26 pm    Post subject: Reply with quote

Ok than it means my lense has aperture problem? Sad but true...


PostPosted: Tue Nov 24, 2009 1:07 am    Post subject: Reply with quote

Sticky aperture probably. Very common problem.

It may be easy to fix if the lens can be opened so you can reach the aperture blades. A little lighter fluid may be all you need.


PostPosted: Tue Nov 24, 2009 7:42 pm    Post subject: Reply with quote

Hi,

Tharos wrote:
Ok than it means my lense has aperture problem? Sad but true...


As already said by luisalegria, this is easily fixed: just browse to http://oomz.net/tessar/ and follow the instructions, i have fixed the blades of my Tessar this way Wink

And the Zippo fluid does the job like a charm ...

Cheers


PostPosted: Tue Nov 24, 2009 8:33 pm    Post subject: Reply with quote

I've given up with them. I had 2 that were the same. I tried to fix one but no dice. I may try again if I acquire one but I think I have this focal length covered (to excess).


PostPosted: Tue Nov 24, 2009 8:56 pm    Post subject: Reply with quote

This is surprising problem, but the Tessar is cheap. The best a/m switches i have seen and used so far are on the Helios 44 and the Meyer Oreston, especially that last, even if the pin is a bit "lousy".


PostPosted: Tue Nov 24, 2009 9:56 pm    Post subject: Reply with quote

martinsmith99 wrote:
...but I think I have this focal length covered (to excess).


Meet your brother - my collection from 50mm through 55mm to 58mm has become quite crazy really Rolling Eyes


PostPosted: Tue Nov 24, 2009 10:31 pm    Post subject: Reply with quote

Sorry to hijack your post, but I think I got similar question on pk mount lens.
I got my pk mount lens today and the aperture does not move at all when rotating the aperture ring. There is no A/M switch or other switch on the body, how can I change the aperture?
Did not used a lot of pentax manual focusing lenses before, so if this is not a problem with the lens, please forgive me.
Thanks in advance,
Wei


PostPosted: Tue Nov 24, 2009 11:33 pm    Post subject: Reply with quote

@ Iwsy: PK aperture has to be kept open by the camera with original mount, the lenses close themself to the indicated aperture when not on camera (or on adapter). So you have a lens with sticky aperture too, that need to be cleaned.


PostPosted: Tue Nov 24, 2009 11:52 pm    Post subject: Reply with quote

Minolfan wrote:
@ Iwsy: PK aperture has to be kept open by the camera with original mount, the lenses close themself to the indicated aperture when not on camera (or on adapter). So you have a lens with sticky aperture too, that need to be cleaned.


Minolfan,
Thanks for the information. Let me repeat to see if I understand this correctly.
When the lens is off the camera and without any adapter, rotate the aperture ring should change the aperture anyway, right? So I need to clean the aperture blades in my case? Could this because something connecting the aperture ring and the aperture blade is loose or not hooked up?

By the way, my lens always keeps at the max aperture position.

Regards,
Wei


PostPosted: Wed Nov 25, 2009 6:52 am    Post subject: Reply with quote

Hi Wei,

Yes. When you take the lens off the PK camera you should be able to change the aperture by rotating the aperture ring.

Your problem could be a stuck aperture, it could also be a broken or misplaced part of the linkage mechanism.


PostPosted: Wed Nov 25, 2009 2:59 pm    Post subject: Reply with quote

luisalegria wrote:
Hi Wei,

Yes. When you take the lens off the PK camera you should be able to change the aperture by rotating the aperture ring.

Your problem could be a stuck aperture, it could also be a broken or misplaced part of the linkage mechanism.


Thanks for the information. I confirmed that it is a problem with the oil on the blades that they are gluing themselves together and kept at the max aperture position. So I will need to clean the blades.