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07-10-2020, 05:58 AM   #1
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Need help with Tokina RMC 17mm lens

I just got an Tokina RMC 17mm lens, f3.5 (M42 screw mount).

Just wondering if anyone can help as I seem to have run into a little problem (I've attached some pics to help illustrate; back of lens, lens with adapter on, adapter and lens side by side)

There is a little metal piece that protrudes out the back of the lens, which moves with the aperture.

I am putting this lens on a M43 mount camera with a speedbooster adapter (M42 - M43).
This little protrusion stops me being able to screw the lens on fully.
When the lens is screwed on, this blocks the movement of the aperture (to open or close the aperture I have to slightly looses the lens from the adapter and then re-tighten it).
The lens looks pretty good and the focus seems to be ok, so this doesn't seem to be causing any noticeable problem linked to the correct flange focal distance.

Here are my questions:
* Is there any way of taking this metal piece out without messing with the aperture?
* Does anyone have experience opening theses lenses? There are 3 screws on the back.

Note: I also have a SMC Takumar lens which works just fine with this setup as the little metal protrusion sits inside the area that is screwed on to the adapter (and not outside as this one does)

Any advice would be very welcome and much appreciated!!

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07-10-2020, 08:17 AM - 1 Like   #2
D1N0's Avatar

Join Date: May 2012
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It has a Fujica ST mount. A variation on m42 with and aperture feeling tab. You need to file it of or get an adapter that is able to accommodate it. Maybe you can take it out when you open up the lens. That shouldn't mess up the aperture.
07-10-2020, 08:59 AM   #3
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Join Date: Mar 2020
Posts: 8
Original Poster
Ahhhh....Thank you for so much clearing that up! I wasn't aware of this type of mount.
I bought this lens because the seller said it was M42.

In any case, it does seem like a beautiful lens...

Ok, I might have a look inside and see what can be done.
Otherwise filing might be a good (but also slightly scary) option.

Thanks again for the information and ideas!

Best wishes

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adapter, aperture, aperture behavior, camera, lens, m42 & adapter, m43, metal, pentax help, photography, piece, protrusion, rmc, screw, tokina 17 mm, troubleshooting
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