Leica LTM Summitar Diaphram Blades

Leica M39 screw mount bodies/lenses
I have two Summitars, a 526... (1939) and a 721... (1948). Both have the round aperture design.

Cheers,
Dez
 
#554xxx 1940, uncoated, round
#901xxx 1951, coated, hex

From Sartorious' book

IMG_6834.JPG
 
1950 model 817xxx hex design. Awesome. When used wide open (as Leica meant it to be used), the aperture shape and number play no role.
 
The hexagonal design was introduced in the last few years of Summitar's production. Supposedly the hex-aperture reduces vignetting/light drop-off in the corners. (Or it was cheaper)....
I've personally never noticed this with my (pre-)wartime 10-bladed Summitars.
 
I use the Summitar almost always wide open, so there is no observable difference between the different model aperture designs.
 
When I was at Leica in Wetzlar this summer, Peter Karbe (Leica Top optical designer) gave our group a talk about tradition and innovation at Leica. He emphasized repeatedly during his 75 minute talk that "[you] must use Leica lenses wide open. They are designed for it." I use lenses wide open to be able to play better with the resulting out of focus in the background.
 
Thank you.

raid said:
When I was at Leica in Wetzlar this summer, Peter Karbe (Leica Top optical designer) gave our group a talk about tradition and innovation at Leica. He emphasized repeatedly during his 75 minute talk that "[you] must use Leica lenses wide open. They are designed for it." I use lenses wide open to be able to play better with the resulting out of focus in the background.
Click to expand...
 
There are situations at which I have to close down the aperture due to strong light, and then I often use aperture 8-11.
 
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