I remember a thread on the RRF where Brian Sweeney took a Helios-103 (a different lens) which comes with lightly blued leaves in the iris and reduced flare considerably by the simple expedient of rubbing a black marker on them and replacing the front element cluster.

He shows a before/after shot of the same scene and the reduction of flare is easily seen. Could it be this Helios suffers from the same problem?


Could be an answer for you.