Helios (lens brand)

Helios (Russian: Ге́лиос) was a brand of camera lenses, made in the USSR. They were usually supplied with Zenit cameras and thus usable with other M42 lens mount cameras such as the Pentax Spotmatic. Some later Helios models were built also for the Pentax K mount.

The Helios-44 and Helios-40 are derivatives of the Carl Zeiss Biotar optical formula. As all lenses based on the Biotar formula, the Helios-44 and Helios-40 produce an unusual "swirly" bokeh effect to the out-of-focus background. The bokeh "circles" become more elliptical in shape as you move away from the center of the photo. This optical phenomenon gives images rendered by these vintage lenses a distinct character, which has created a cult following among fine art photographers.