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04-25-2013, 12:33 AM   #1
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Mamiya Sekor SX Auto 55mm f1.4

I picked up a Mamiya Sekor SX Auto 55mm f1.4 M42 lens a few weeks ago based on the reviews on the forum. Didn't quite read far enough to discover the pin and aperture ring problem with fitting this lens.

I then found what other people had done to make them work, but for many days I couldn't bring myself to touch the lens as it is beautiful made and in pristine condition. Eventually though I figured if I was careful I could file the ring down and make it work.

The way I did it was to cover flat surfaces with insulation tape then with a fine file, worked the edge done until the file just started to snag the tape. This gave enough clearance for the ring to rotate freely when mounted.

Next problem was how to hold the aperture pin down. After discovering that the M42 adaptors are chrome plated brass, I filed a portion of the coating off and soldered a small tongue onto the adaptor. It was tricky getting enough heat into the adaptor with a soldering iron, so to solve this I sat the adaptor on one of the hotplates of our ceramic top kitchen stove. In conjunction with the soldering iron, it worked a treat.

I was a bit nervous the protrusion would catch on the insides of the camera but some very careful trial fitting showed that it fitted just fine.

Its just getting dark now so its too late to give it anything other than rudimentary test to make sure it works. What really surprised me was how little the viewfinder darkened when stopped down to f16. Attached are a couple of photos of my mods.


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06-14-2013, 04:48 PM   #2
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Looks good if it works well. Those SX lenses are really beautiful. I came across an SX 21mm f4.0 once and could not bring myself to try anything with it. I took some photos with it on the Spotmatic I got it with and they were really sharp and detailed. I ended up selling the lens. Make sure you post some photos with it.
06-14-2013, 11:48 PM   #3
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QuoteOriginally posted by tonksj Quote
I was a bit nervous the protrusion would catch on the insides
It is an m42-k adapter with a knob that can push the aperture pin down to give stop down metering. It is a nice feature, some M42 lenses do not have M-A switch and one will have to glue the pin. With this adapter, you don't have to do it.
A very nice lens. Enjoy it!

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