I posted this set of pictures the other day in the LF forum but got very little response. I'm hopeful that someone can tell me something about this type of lens so I risk the wrath of the photo gods and the moderators by repeating some of it here. This lens baffles me in that there is no flange and no shade on the front but there is an stop plate some halfway down the barrel. The image circle is about 4". Maybe a quarter plate camera? The plate in the barrel moves, though it is not clear that it should. Any sense of where it should live, front to back? top view side view and the picture taken with it.