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01-06-2014, 04:04 PM   #1
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Super-Takumar 50 f/1.4 f-stops

I have a quick question about the aperture ring on the Tak 50 f/1.4. Every full stop is marked with a number except for f/2. Everywhere else in the aperture range, there's a click for every half-stop, too. Between f/1.4 and f/2.8 (two full stops), there's two clicks. Which one's f/2?

In other words, the aperture ring clicks are:


So, what are those two mystery clicks? f/2 and f/2.5? f/1.8 and f/2? I know it doesn't matter all that much, but these things bug me.

01-06-2014, 04:41 PM   #2
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I saw a quote from a lens manual for one of the Pentax 6x7 lenses. It explained that the first click, marked with a large white dot on the ring, was one full stop down from wide open. But that's a marking system more common on K series lenses. (One example is the K135/2.5.) That would be f2 for the first click and f2.4 for the second.
01-06-2014, 04:52 PM   #3
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Ah! Thanks for clearing that up, Dave. I figured the click with the dot on it would be the full stop, but I wanted to make sure. The SMC version omits the dot.

I also just noticed that there's no half-stop click between f/11 and f/16. Weird...
01-06-2014, 05:11 PM   #4
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In the service manual here for Super-Takumar 50 f/1.4, there are 3 models: 358, 378, & 37801.
The photos for the first two show labels 1.4, 2, 2.8, 4, 5.6 8, 11, ......
The photo for the 37801 is of the other side of the lens. ...5.6, 8, 11, 16
There is no info on the click stops.
The diagrams for the 358 and 378 are similar and some parts in that area are listed as interchangeable , the 37801 is different.

01-06-2014, 08:24 PM   #5
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f2.0 (white dot)


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aperture, clicks, f/1.4, f/2, f/2.8, k-mount, pentax lens, slr lens, super-takumar 50 f/1.4, takumar
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