Swirly Bokeh from Helios 44M lens, this lens is optically a Carl Zeiss Biotar copy.
The Helios 44M-7 i have used for the photo's lens can create a nice swirly bokeh at full lens opening, this is because when the aperture is closed (above F2) the opening is no longer round, the opening becomes a hexagon due to a 6 blades only aperture, with will lead to a lesser bokeh. (sunrays are a point and therefor round).
Earlier version like the 44M-2 has 13 blades for a nice round opening at every aperture and a smoother bokeh, but also has a lower resolution in center and corner sharpness
Therefore it is preferred to buy the Helios 44M-2, if you want a nice bokeh over the whole aperture range. The 44M Or -6 -7are sharper over the whole range.
But then, the Helios 44M price ranges from 35 till around 80 $ and is still a bargain, mine came from the local thrift shop for around 5 euro.
original Carl Zeiss Jena Biotar 58mm F2 second version has 17 aperture blades !, the more aperture blades the rounder the opening stays when closing the aperture down and the smoother the bokeh over the whole aperture range.
Looked it up on Ebay:
The original Carl Zeiss Biotar 58mm F2, depending on condition version and mount (M42 or Exacta bayonet), sell on average between 150 and 350 us $
So for Swirly Bokeh loving photographers, the Helios 44M is the way to go, its a bargain at current prices.
For collectors , stick to the orginal Carl Zeiss Biotar 58mm and buy it in mint condition only.(investment).
For collectors/photographers swimming in money, go for the king of Bokeh, the legendary Carl Zeiss Biotar 75mm F1,5 !
Swirley Bokeh explained:
Helios 44M review:
hope you like it, greetz len.