There are several variations of this lens all with different character. They are all similar and different but built with the same goal – to copy the Zeiss Biotar.
If you’re looking to get started collecting old vintage lenses from the 80’s and 90’s, then the Helios 44 series is a great place to start. They are known for their beautiful large swirling bubble bokeh.
One of the more interesting vintage lenses is the Russian made M42 mount Industar 50mm f3.5 pancake lens.
The Industar has won lots of praise over the decades and people really seem to love it. So is the lens good?