A while back a friend gave me a pair of un-used Zorki-4 and Zenit-B cameras. Complete with paperwork and original receipts from USSR. The Zorki-4's signed 'Certification Document' indicates the lens develops 31 lines/mm at the center and 14 lines/mm at the edge wide open. I checked the the Helios-44-2's certificate to see if the resolution is indicated but it just says "meets the technical requirements and is admitted to be useful."