MC Helios-81H 2/50 (or MC Helios-81H 2/50, or Arsat H 50mm 1:2) is one of the best regular lenses from the Helios family.
Such a lens is most often called a 'fifty kopeck' because of the focal length of 50 mm.
On full-frame cameras (film and digital cameras with a frame size of 36 x 24 mm), it is standard (in terms of focal lengths and angle of view) and is suitable for everyday use for a wide range of tasks.
On modern cropped cameras, Helios-81 can also be used well as a portrait and creative lens.
In my opinion, Helios-81 earned its popularity due to its compatibility with Nikon digital SLR cameras with Nikon F mount. .
Also, the popularity of the lens is associated with a special twist of the background, characteristic of many lenses of the Helios family, as well as good optical capabilities for a fairly low cost.