Mamiya Sekor sx 135mm 2.8 assembly

Started 4 months ago | Questions
Nickyvidz89 New Member • Posts: 18
Mamiya Sekor sx 135mm 2.8 assembly

So, I just got a brand new Mamiya Sekor sx 135mm f2.8.

I was attempting to modify the aperture pin as I do many other m42 lenses, but after taking this one apart I quickly learned I have no idea how to re assemble it. I can't find anything online in terms of a service manual, does anyone know of a link they could share as to re-assembly ? When I put the aperture ring back over top the lens I can only get the aperture to change by rotating the entire end piece, aperture ring and mounting ring, as opposed to just the aperture control ring itself. I know this lens has another little pin in it I am wondering that could have something to do with it but I am not sure. Maybe I am missing a piece?

I will add photos soon to show where I am. Thanks in advance.

ANSWER:
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Aoi Usagi Senior Member • Posts: 2,812
Re: Mamiya Sekor sx 135mm 2.8 assembly

Please upload some photos that shows us your problems with the lens.

Albert Silver Veteran Member • Posts: 3,373
Re: Mamiya Sekor sx 135mm 2.8 assembly

Nickyvidz89 wrote:

So, I just got a brand new Mamiya Sekor sx 135mm f2.8.

I was attempting to modify the aperture pin as I do many other m42 lenses, but after taking this one apart I quickly learned I have no idea how to re assemble it. I can't find anything online in terms of a service manual, does anyone know of a link they could share as to re-assembly ? When I put the aperture ring back over top the lens I can only get the aperture to change by rotating the entire end piece, aperture ring and mounting ring, as opposed to just the aperture control ring itself. I know this lens has another little pin in it I am wondering that could have something to do with it but I am not sure. Maybe I am missing a piece?

I will add photos soon to show where I am. Thanks in advance.

If the lens has a pin on the rear end then it needs to be pressed for the aperture ring to work.

 Albert Silver's gear list:Albert Silver's gear list
Nikon D750 Nikon AF-S Nikkor 70-200mm f/2.8G ED VR II Sigma 24-105mm F4 DG OS HSM Tamron SP 35mm F1.8 Di VC USD +1 more
OP Nickyvidz89 New Member • Posts: 18
Re: Mamiya Sekor sx 135mm 2.8 assembly

.

Aperture ring

Aperture lever

.

Aperture lever (left)

Preview lever (right)

.

Ring

Modified aperture pin

Which of these levers does the aperture spring go against? I thought it was the aperture preview lever on the right, but then there's is nothing that pushes up against the arm that controls the aperture setting so it won't change when you turn the ring. Please forgive my lack of technical part names. Thanks!

OP Nickyvidz89 New Member • Posts: 18
Re: Mamiya Sekor sx 135mm 2.8 assembly

Actually I think I just got it 😂

OP Nickyvidz89 New Member • Posts: 18
Re: Mamiya Sekor sx 135mm 2.8 assembly

I got it I just didn't have the lever attached correctly. I now have a fully working declicked aperture ! Thanks guys!

scrup Contributing Member • Posts: 526
Re: Mamiya Sekor sx 135mm 2.8 assembly

I see a few posts about modifying the pin. What is the issue with the pins?

I have a few m42 lenses and never had to do any surgery on the pins to get them to work properly adapted.

Just curious what people are doing to these lenses.

 scrup's gear list:scrup's gear list
Canon EOS M Canon EOS M3 Canon EOS M6 Canon EF-M 18-55mm f/3.5-5.6 IS STM Canon EF-M 22mm f/2 STM +2 more
Aoi Usagi Senior Member • Posts: 2,812
Re: Mamiya Sekor sx 135mm 2.8 assembly

Nickyvidz89 wrote:

I got it I just didn't have the lever attached correctly. I now have a fully working declicked aperture ! Thanks guys!

Congratulations on getting it back together.  Let us know what you think about its image quality.

Aoi Usagi Senior Member • Posts: 2,812
Re: Mamiya Sekor sx 135mm 2.8 assembly
1

scrup wrote:

I see a few posts about modifying the pin. What is the issue with the pins?

I have a few m42 lenses and never had to do any surgery on the pins to get them to work properly adapted.

Just curious what people are doing to these lenses.

I suspect the OP has a adapter without the ledge to depress the stop down pin.  Without the ledge in the adapter, and the fact that SX lenses don't have Auto/Manual switches, modifiying is the only option.  Mamiya Sekor SX lenses have another pin on the the back side of the aperture ring for open aperture metering that also needs to be removed, as well as a lip on the outer circumference of the aperture ring that may cause it to bind on certain adapters.  Many people grind down the aperture ring and remove the pin.

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