Does it really add up significant cost to the lens to have a 9 rounded aperture blades for a lens? Cos I find that lens that have 9 aperture blades tends to produce better bokeh. Eg. I have the 50mm AFD1.8, at f1.8, the bokeh is still rounded but when I reduce the aperture to f2.8 onwards, it start to produce hexegon shape bokeh.
Is there really a lot of cost savings to the production to have a 7 aperture blades instead of 9 and compromise on the bokeh?