Archived posting to the Leica Users Group, 1996/11/28

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Subject: Re: Number of Blades
From: Marc James Small <msmall@roanoke.infi.net>
Date: Thu, 28 Nov 1996 15:43:08 -0500

Chris Fortunko has commented on the decreasing number of aperture blades in
Leitz/Leica lenses in recent years.  I suspect two factors -- reducing
production costs while designing the lens with extreme precision to minimize
the adverse effects caused by the smaller number of blades -- have combined
to bring this about.

In a similar vein, Wartime lenses have few blades, too, this having been
caused by the extreme scarcity of the sort of fine steel used in these
blades.  Nonetheless, the Summitar -- the star lens of the Leica line-up --
had thirteen blades or so in its aperture assembly, though this was reduced
to six by 1950 (or so the books say, but my '49 739077 also has six).  At
the very end of production, from '51 on, the aperture assembly is back to
eleven blades, but by now doubled, so that the aperture assembly looked like
a process lens of some sort.  I don't know what this means!

Hassie lenses and most Rollei TLR lenses have cheerfully lived with five
blades for decades.

Marc

msmall@roanoke.infi.net  FAX:  +540/343-7315
Cha robh bas fir gun ghras fir!