For Series 1, of the manual focus era, there are two considerations. First is actual manufacturer, Vivitar used many on Series 1, and quality supposedly varied. Ideally you buy one that has serial number starting with 28 indicating Komine was the manufacturer. For more about this subject see: htt p :
www.robertstech.com/vivitar.htm
I have two Komine/Viivitar's for my Nex and they are nice. I haven't tried the others because I'm not that into experimentation.
As for mount, for manual lenses you buy one for $20 on ebay. They are just a metal tube of the right length with the right connection on each side. I'd recommend either Canon FD or Nikon F, since after buying one of those adapters you get access to lots of high quality old lenses. You could also buy the first Series 1 that looks good and choose your mount to match it, but again one Canon FD or Nikon F adapter opens up the biggest world for you.
Most people say to stay away from manual focus era superzooms, like 28-200, because they weren't very good back then. I can't offer first hand testimony since I have followed the accepted wisdom. I can say that the old primes are great and the old telezooms are ok but big and heavy compared to today's stuff.
You don't need a tripod at 200mm (300mm w crop factor) for outdoor shooting. You might like to have one, but you can easily get sharp pictures. I've actually shot at 400mm (600mm with crop factor) on the Nex without a tripod, but trying to hold it steady enough to focus is unpleasant and so difficult you will probably miss any subject that moves faster than the Great Pyramid.
I have, however, arrived at the "outside the box" conclusion that I am going to get the best results with a "low light camera", the Nex, and a bright light camera that is a superzoom point and shoot that comes with a zoom that goes up over 800mm. I think the thing to do is to match the sensor size to the light. For low light you need a big sensor. When you have bright outdoor light having the zoom flexibility of a 25-800mm lens in a "fits in your hand" package can't be beat. Image quality is fine and you can't tell me that "you never need 800mm" or that "I'll always have that zoom range handy for my APC size camera when I want it" Rather than change lenses, indoors to out, I change cameras.
Got it for $120 shipped from eBay 
