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Mamiya Sx lens auto diaphragm pin modification and adapting.
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PostPosted: Wed May 04, 2011 7:45 am    Post subject: Mamiya Sx lens auto diaphragm pin modification and adapting. Reply with quote

I have done this a few times now and thought I should share it here. The auto diaphragm pin mod. is very popular and I am sure most of you are familiar with it.
The Sx lenses have an additional problem , that is the aperture ring has a rim that rises higher than the plate of the mount, which hampers the free movement of the aperture ring, and there is also the loss of the ability to focus to infinity. My apologies for any typos.

This was done on the Auto mamiya/sekor sx 105mm f2.8.






Last edited by Kathmandu on Wed May 04, 2011 7:54 am; edited 1 time in total


PostPosted: Wed May 04, 2011 7:48 am    Post subject: Reply with quote








Last edited by Kathmandu on Wed May 04, 2011 7:51 am; edited 1 time in total


PostPosted: Wed May 04, 2011 7:50 am    Post subject: Reply with quote







PostPosted: Wed May 04, 2011 11:43 am    Post subject: Reply with quote

Nice work and nice tutorial. Thanks


PostPosted: Wed May 04, 2011 1:02 pm    Post subject: Reply with quote

Agree, well done!


PostPosted: Wed May 04, 2011 3:03 pm    Post subject: Reply with quote

Nice account. Thanks.


PostPosted: Mon May 09, 2011 1:29 pm    Post subject: Reply with quote

This is fantastic.

I'm having trouble unscrewing that aperture status pin with tweezers/needle nose pliers. Anyone have some tips on getting that pin out?

Best,

Isham


PostPosted: Fri May 13, 2011 12:50 am    Post subject: Reply with quote

Schnauzer,Katastrofo,sichko, & IRR_DC: Thanks a lot .

Isham ,it would be nice to see some pictures with your newly adapted lens.

Update:He was able to get the pin out with persistence. Smile. He was able to pull it out unscrewing it clockwise. These pins are not threaded and some require a little persuasion and persistence.


PostPosted: Fri Jul 29, 2011 5:05 pm    Post subject: Reply with quote

I'm having trouble with unscrewing the aperture pin. Could you tell me if it is clockwise or counterclockwise?
I suppose I'll try "persistence", but right now the pin is winning me in that... xD


PostPosted: Fri Jul 29, 2011 6:26 pm    Post subject: Reply with quote

quique_fs wrote:
I'm having trouble with unscrewing the aperture pin. Could you tell me if it is clockwise or counterclockwise?
I suppose I'll try "persistence", but right now the pin is winning me in that... xD


I went over this exact same problem with someone before-and his was anticlockwise. Mine was clockwise. Which makes me believe the pin is not threaded in. Its either glued or put in there when hot?.

The thing to do is to put some isopropyl alcohol or similar solvent over the pin-a dab, not much. Grab the pin firmly -with a pair of tongs ,or any thing that has grip on it- then wiggle it slowly , turning clockwise and then anticlockwise-until it comes out.

Hope it works for you. Very Happy


PostPosted: Sat Jul 30, 2011 9:26 am    Post subject: Reply with quote

Thank you very much por your answer. I also think that the pin is inserted by pressure instead of screwed.

I'll try the isopropyl alcohol, because the pin is firmly stuck and I can't get it out. I'll tell you if I have success Wink


PostPosted: Sat Jul 30, 2011 6:46 pm    Post subject: Reply with quote

quique_fs wrote:
Thank you very much por your answer. I also think that the pin is inserted by pressure instead of screwed.

I'll try the isopropyl alcohol, because the pin is firmly stuck and I can't get it out. I'll tell you if I have success Wink


Cool, sounds good -also may try hair dryer at warm setting with back cap of lens closed -of course you don't want to melt anything. Very Happy


PostPosted: Tue Oct 28, 2014 6:43 pm    Post subject: Reply with quote

I know this is an old thread but I wanted to report that I got a Pixco M42 to Fuji FX adapter on ebay and it is smaller in diameter than the Rainbow Imaging ones. Therefore, it clears the outer lip of the SX lenses and seats firmly without having to file down either the adapter or the lip on the lens. With this adapter, there is also no need to surgically remove, depress, or glue down the auto diaphragm pin with it. However, the pressure fit aperture pin still must be removed which is doable with some patience and a pair of tweezers.


PostPosted: Fri Aug 07, 2015 11:26 pm    Post subject: Reply with quote

Instead of creating a new thread, I thought it best to post in this informative thread on the Mamiya SX lenses.

I need some help!
Been aware that the SX line of lenses had required extensive modification to be used on other M42 based camera bodies and older adapters. So, I avoided them.
But their positive reputation, plus the idea that this line was made in-house by Mamiya and not by Tomioka as previous 35mm format lenses, had fueled my LBA and resistance was futile.
Smile

Opportunity reared itself for a pair of SX lenses, a 50 f/2, and 135 f/2.8. The 50 was dirt cheap, but the 135 cost me 200%+ what I could have paid a year ago. (Yes, foolish of me!)

Back to the problem....

I have an adapter now designed for clearing the lip of the SX aperture ring. Plus, it's flanged to depress the auto aperture pin. My only mod was to remove the stainless steel pin from the ring.
But before I could even try them on the camera, I noticed something that didn't appear correct.
Depressing the auto pin by hand, didn't operate the blades. Held down, turning the ring to either end also didn't operate the blades. Both lenses are wide open. Both lenses don't show signs they were modded, and are in pristine condition, albeit stiff focus rings due to age.

I've owned Yashicas, Tomiokas, S-M-C Takumars, and understand the pin's operation. But these two SX's don't seem to want to work.
Am I missing something unique to these that I overlooked?
I find it too coincidental that both lenses aren't operating.

Thanks in advance for any insight and exprerience you can share.