The Helios 44-2 is a legendary Soviet lens, produced in enormous quantities from the 1950s onwards at the KMZ factory. It is a copy of the pre-war Zeiss Biotar 58mm f/2 design and is famous for its distinctive swirly bokeh rendering, caused by the optical formula producing a characteristic out of focus pattern in backgrounds with fine detail. Sharp in the centre wide open, it has become hugely popular with portrait and creative photographers seeking a distinctive look.

Fun lens - a little strange - at least on mine - the f stop markings do the opposite of what you would normally think - put the red marker/label against F16 and that is the LARGEST aperture - i.e. F2 and vice versa - F2 = F16.