I have this lens (And many others for the RZ system). Seiko makes all the shutters, and always has. The missing name is odd but nothing to worry about. 50ULD is a fantastic lens, esp. considering it's a retrofocus design. Even the normal non-ULD 50 is a very good lens (despite what you might read online). Really, basically all the lenses in the RZ system are excellent, no real dogs that I have encountered so far.