I wasn't sure if this should be posted in this forum or the lens forum, but since it came with an enlarger and mounted on a Beseler board I figure more info might be here. The aperture ring is marked 1,2,4,8,16,32. From what I found on a quick search was it appears to be a macro lens? How and why would you use this lens in a darkroom? It seems to be kind of rare. I checked ebay for completed and current and there are none.