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01-30-2011, 08:26 AM   #1
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Join Date: Jan 2011
Location: Mt. Akagi, Gunma Prefecture
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SMC Tak 150mm/4 threading

Today I found a reasonably clean copy of the Super-Multi-Coated Takumar 150/4 for about $40 and brought it home since that is a focal length I don't have.

It works fine but the threading is off. Screwed all the way in the center mark is considerably short of TDC; stopping somewhere around 10:30 or 11:00 instead of the normal 12:00.

This happens with my James Lao chipped adapter and also when screwing it directly into the Pentax Spotmatic. And strangely, on the spotmatic it feels really tight, although it does go the normal 2.5 rotations before stopping.

Now I've heard of other brand M42 lenses having threading problems that result in something other than TDC, but of the dozen or so Takumar lenses I've owned this is the first one that didn't stop right at TDC. Have I just been lucky so far? Or is this unusual for an SMC Tak? I don't imagine there is anything I can do about it...

The biggest problem it causes is on the Spotmatic where the light meter no longer works when the lens is in auto mode because the pin on the lens butt isn't aligned with the lever in the camera that is supposed to hit it when you turn on the meter so the lens remains wide open. Of course the easy workaround is to meter in Manual mode.

01-30-2011, 09:26 AM   #2
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I see similar behavior


I have an SMC Tak 150mm and it mounts correctly on my Spotmatic SP ... meaning that the red diamond on the distance meter is positioned at the top of the lens at "12 o'clock."

However, using a genuine Pentax m42 to K adapter on my K-7, the lens does not line up the same way, with the red diamond slightly to the right of top (1 o'clock) if you hold the camera as if you were taking photos.

So, while I can't say this is correct behavior, I can duplicate it on my K-7.

Actually I think MOST of my screwmounts never sit TDC as you describe, they're always a little off. Never gave me any issues.

Welcome to the forum and good luck.

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k-mount, lens, lenses, meter, mode, pentax lens, slr lens, smc, spotmatic, tak, takumar, tdc
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