Extra aperture(s) on summicron?

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When I open up the aperture on my 35mm Summicron M, I can open a little wider that the f/2 detent. I assume this is normal. Any idea how much extra light I'd get by holding it there while shooting? Just curious, TIA.

-Steve

-- Steve Reczkowski (czks2@yahoo.com), May 06, 2001

Answers

Steve, a leica lens technicion told me their lenses are all individually calibrated for maximum f-stops, so the slight closing down of the blades will equal f2.0 in your case. Because of this, many of the newer lenses open up a bit further than the maximum aperture. My 90 2.8 Elmarit does this as well. I figure I actually have an f2.7 or something silly like that. Maybe you have an f1.95 Summicron. In any practical terms, that 1/8 or 1/10 of a stop will not be noticeable even on slide film.

-- Andrew Schank (aschank@flash.net), May 06, 2001.

My 35/2 asph does the same thing.

-- sam smith (ssmith@hotmail.com), May 06, 2001.

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