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Re: [OM] ...blades & bokeh....

Subject: Re: [OM] ...blades & bokeh....
From: Winsor Crosby <wincros@xxxxxxxxxxxxx>
Date: Fri, 27 Aug 1999 18:31:07 -0700 (PDT)
Morgan wrote:
>
>The auto-diaphragm must be a big determinant in the number of blades.
>My impression is that most manual/preset lenses have alot of blades.  My
>old preset 105 2.8 has 14 of them, forming a near-perfect circle at all
>settings.
>
>The quick-return diaphragm is relatively complicated compared to a
>manual one. . . .I think it took Asahi a couple of years to perfect
>theirs after they brought out the original Pentax.  The first Canonflex
>SLR's used a charging pin . . . . when you wound the film you also
>pre-tensioned the diaphragm.  If more blades equals better optics, then
>are most modern lenses a compromise?

Not unless you see a SLR as a compromise. Complicated retrofocus lens
design and complicated automatic diaphragms are not needed on modern Leica
lenses. I am not sure whether blade number is limited by the complexity of
an automatic diaphagm.  It is certainly simpler than a non focal plane
shutter which does not have substantially fewer blades.

I am not sure how many blades were in the lenses of my long stolen Leitz
lenses. It might be interesting to find out whether the number of blades
has been reduced in the modern rangefinder lens designs.

Winsor

"I have the heart of a small boy -- and I keep it in a jar on my desk." -
Stephen King

Winsor Crosby
Long Beach, California, USA
mailto:wincros@xxxxxxxxxxx





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