I found a Mamiya-Sekor C 45mm f/2.8 lens today in the junk bin for something like $60. It is rather dusty and the focus ring feels a bit stiff but other than that it seems ok... no mold! which was my biggest worry since I didn't have a good flashlight with me when I was at the store.
Anyway, the unusual thing about this lens is that on the front ring right between where it says "Mamiya-Sekor C" and "1:2.8 f=45mm" there is the word "SAMPLE" in red print. Also, the serial number shown on the same ring is No.10009
Is this some sort of first production run lens that was made to be used as a sample? Has anyone seen this sort of thing before?