Sorry, I don't know who to attribute this to
Some lens manufacturers have tried to pass off the notion that more closely circular aperture diaphragms with more blades and/or curved blades are they key to good bokeh. That's marketing BS: Aperture shape can affect specular highlights, but doesn't do much for bokeh.
It might have less to do with the aperture shape because bokeh is primarily a phenomenon of using the lens with a fairly open aperture.
William Robb
