As we are all aware, the more blades there are in a lens’s diaphragm, the rounder the resulting hole can be made, and in turn this gives a more natural looking bokeh.

So on receiving my recent Hasselblad Carl Zeiss distagon 4/50 lens, i was rather, well, confused, to see that it has a straight-cut 5-blase diaphragm, basically leaving you with a pentagonal hole as an aperture...

I have yet to compare its results to my 9-blade Nikkor 50mm 1.4f, which has a "near as damn it" circular aperture at all f-stops, so I want to know, is this decision for a particular reason? does it give a certain "zeiss look"? Its certainly not a technical limitation of its age.

(For reference the lens was made in 1985)


1 Answer 1


Believe it or not, this fascination with "good bokeh" is a relatively recent phenomenon, at least outside of Japan. The first indication I ever saw of it as "a thing" was when the Minolta 135 f/2.8 [T 4.5] STF was released (admittedly, it goes a little further down the "good bokeh" road than any other lens). When I took up photography, doing things with the pentagonal or hexagonal aperture shape (especially with flare) was the trendy thing to do.

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    \$\begingroup\$ I await the day when photo blogs are abuzz with the hot new phenomenon of bee-hive bokeh :) \$\endgroup\$ Aug 27, 2012 at 17:29
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    \$\begingroup\$ Ah, the endless wealth of knowledge that streams forth from Stan's brain...I love these little tidbits of lore! :) +1 \$\endgroup\$
    – jrista
    Aug 27, 2012 at 18:42
  • \$\begingroup\$ Sure? Lens designers tended to use very high numbers of aperture blades (often 13, 17 or so) until the advent of automatic apertures in SLRs forced them to use a design that could be actuated quicker with less force required... \$\endgroup\$ Mar 29, 2021 at 9:00

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