g Helios-44-2 OMZJ f2/58mm Russian Lens of M42 mount Zenit Praktica camera 0426
The Helios 44-2 features a maximum focal aperture of f/2.0. High focal apertures yield pictures with detail finer than what is perceived with the human eye. Focal length varies a little in this 58 mm f/2.0 lens from 58-60 mm.