Via: http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=40088160
It has even two more blades for what I saw and reported for the last time:-
http://ricehigh.blogspot.com/2010/11/round-lens-diaphragm-see-this-o.html
Wonderful! The bokeh of this Takumar must be good! And, Pentax wins (won actually) other once again, eventually! ;-D