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Does the russian OKC (OKS) lenses use F- or T-stops?


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#1 Tomas Stacewicz

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Posted 15 September 2006 - 06:19 PM

Does the russian made OKC/OKS prime lenses (used together with the Kinor-16 SX-2M) use F- or T-stops?

I have a OKC3-10-1 and on the front of the lens it says 1.8/10 (that is f.1.8) but on aperture ring it has 2.1 as the lowest value. Does the 2.1 signify a T-stop?
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#2 Thomas Worth

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Posted 15 September 2006 - 09:08 PM

Yes, the Russian lenses are marked in T stops. The 1.8 is the maximum f/stop according to the aperture size / focal length ratio, but the maximum transmission is T2.1. So, use that figure in determining exposure.
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#3 Tomas Stacewicz

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Posted 16 September 2006 - 03:18 AM

Thank's
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#4 Olex Kalynychenko

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Posted 16 September 2006 - 10:36 AM

Does the russian made OKC/OKS prime lenses (used together with the Kinor-16 SX-2M) use F- or T-stops?

I have a OKC3-10-1 and on the front of the lens it says 1.8/10 (that is f.1.8) but on aperture ring it has 2.1 as the lowest value. Does the 2.1 signify a T-stop?


A few time ago, i sent answer on sumilar question.
You can check letters about this.

The russian lenses have marks of geometric aperture on front side near full name of lens " OKC-3-10-1 1.8/10 " 10 mm, F1.8, and have marks of T stops on ring of aperture control T2.1.
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#5 Tomas Stacewicz

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Posted 16 September 2006 - 11:07 AM

Thank's Olex! I did a search but didn't find any information about this.
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