Just bought a Vivitar Macro 70-300 mm lens f/4.2-5.8 MC off of ebay for $50. I thought the MC meant it was the Minolta mount (adapter that I have), but I've come to learn that's not the case. It more than likely means "multi coated". Correct me if I'm wrong. So, I have a message into the seller to see if he can tell me what mount it is, but no response so far. I know it's a long shot, but can anyone tell what mount this is by looking at the picture? Also, I would like to buy a 2x teleconverter (or extender, not sure what you actually call them) to double the zoom. Does anyone have this lens that can tell me exactly what to buy or link me to the exact one? I am new to photography and don't want to muck this up. Although I would need to know what mount first, I know. Thanks in advance for any help.