I picked up a weird lens recently. Basically, it's a Tamron adaptall 2 300mm lens which seems to have had the original fitting removed and a simple tubular mount put in its place. The protruding bit is 41mm diameter and about 19-20mm long, the bit at the end that looks like a screw fitting is actually just a groove in the tube. My guess is that it's supposed to click into some sort of quick-change mount, maybe for a cine camera or something of the sort. It'd be nice to know before I try to sell it. Anyone got any any ideas?