FWIW, I count 11 blades on the M-Summicron 90/2 Apo. I'd be surprised if
the Elmarit-M has many more, probably less. 15 blades is a LOT. I
wouldn't expect to see that many on anything short of the bigger longer
lenses like a 180/2 or larger which are SLR lenses.
BTW, the Zuiko 90/2 Macro has 9 blades.
Skip
At 2/9/00 08:52 AM -0500, you wrote:
I think that the number of blades in a lens is at leasty partly a
function of the fact that these lenses are for SLR cameras as opposed
to rangefinder types. I a previous post, someone mentioned that the
Leica M-elmarit 90mm lens had about 15 blades. Since there is no
automatic diaphram in a rangefinder camera, a manufacturer can increase
the number of blades without interferring with the operation of the
camera. The more blades there are in a lens, the more friction in the
mechanism. If there is too much friction in the mechanism, then there
would be a good chance that the diaphram would bind and/or the spring
tension required to return the diaphram to wide open would be too much
for the actuating mechanism in the camera body to handle without
breaking. It would also seriously impact motor drive capability in a
SLR type camera. The motor drive in a rangefinder camera only operates
the shutter and film advance, not the diaphram.
-----------------------------------------------
Skip Williams
Westfield, NJ
skipwilliams@xxxxxxxxx
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