Though the J9 lens I have is M42, I like this lens so much with its beautiful 15 blade aperture, my SLR is a "virtual fixed lens" portrait camera and have a camera body devoted to this terrific lens. Never understood why people complain about the delimiter ring. No brainer. Comes in handy, to me, on those rare instances when I use a thrystor flash unit in auto mode. Otherwise, I just leave it open and rotate it until I get a good reading using the in-camera meter.
One of the great bargain portrait lenses...
Great pics by the way...