Ten blades is better than 5 blades because the spikes are half the width on defocused points. Newer Canon lenses have been 9- and 10-bladed. Hasselblad's old

Ten blades is better than 5 blades because the spikes are half the width on defocused points. Newer Canon lenses have been 9- and 10-bladed. Hasselblad's old V system lenses had 5 blades, curved in C lenses and straight in CF and later. Fun fact for manga fans: the heavy use of Hasselblads in fashion and the resulting pentagonal bokeh lives on today in the frequent appearance of pentagons in the screentones of shoujo manga.