Mamiya/Sekor SX 55/1.8 - Adapter Success!

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Travis Butler
Travis Butler Senior Member • Posts: 1,355
Mamiya/Sekor SX 55/1.8 - Adapter Success!

So, to follow up on this post :

What I was thinking is that instead of modifying a standard M42-M4/3 adapter - which would involve removing the plate with the 42mm screw socket, then filling down the entire body at the rim to provide clearance - you would take an M42-Minolta adapter, which is essentially just a plate with the M42 socket on one side and a Minolta SR bayonet on the other side, and file down the edge to reduce the plate's diameter.

I visited my dad this weekend for Father's Day, and he did have the tools needed to modify the adapter! After trying and failing to file down the edge by hand, he found a specialty drill bit that was just the right width (with its plastic sleeve) to fit the SR throat of the M42-Minolta MD adapter. Took some work with a couple of metal files, a grinding disc, a powered rotary grinder, a sharpening stone, and a fine-grit sandpaper block... but the end result was a modified adapter that clears both the raised edge to the adapter ring, and the pin that engages the aperture mechanism on Mamiya SX bodies.

Original adapter ring at top, modified ring at bottom

Adapter ring on lens - aperture pin circled, showing clearance

Now the lens mounts just fine in a Minolta MD/SR adapter.

Some initial pics...

E-M1 II, Mamiya/Sekor SX 55/1.8

Seemed to do pretty well with the indoor cat test; nailing focus was tricky, but the fur was decently sharp when in focus.

Outdoors is where things got interesting.

It did not look like this in the viewfinder. But while I'm not fond of the composition, the bokeh is 'interesting', the right side is almost watercolor impressionistic, and maybe even a bit of swirl.

This one's a lot more conventional, but do like the OOF rendering.

And this one's pretty conventional.

It does pass my 'clouds' test! Although I definitely had to play with the contrast to bring out all the billows.

A note on the handling: with the adapter properly modified, the aperture ring was almost silky smooth, but the focus ring was actually fairly stiff. The lens has a nearly 360 degree focus throw, which generally I quite like (I prefer precision to speed in focusing), but it was a bit tiring with the stiff helicoid.

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 Travis Butler's gear list:Travis Butler's gear list
Fujifilm X20 Nikon Coolpix A Pentax Q Pentax K-50 Panasonic Lumix DMC-GM5 +18 more
Olympus E-M1
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