50 lux ASPH is part# 11891
It was introduced in late 2004/early 2005 along with the 75 cron APO. These were the first ever M lenses with floating elements.
As I said, the 50 lux-R (E60) is a very solid performer, but not quite as sharp wide open as the 50 ASPH M. I found that I often chose to take the 60 Macro over the 50 lux to cover the mid focal length. Having both a 50 and a 60 in my bag just didn't work for me. YMMV, of course.
David
It was introduced in late 2004/early 2005 along with the 75 cron APO. These were the first ever M lenses with floating elements.
As I said, the 50 lux-R (E60) is a very solid performer, but not quite as sharp wide open as the 50 ASPH M. I found that I often chose to take the 60 Macro over the 50 lux to cover the mid focal length. Having both a 50 and a 60 in my bag just didn't work for me. YMMV, of course.
David