Vivitar 200mm f/3.5 Screw Mount

There is one at a local thrift store. Although it is only $10, I'd have to get an adapter for it and it would likely need to taken apart and cleaned. The glass appears to be in good shape but there is a visible bit of "fuzz" inside. In good condition these are $75 or more on eBay.

It would be an interesting project but I'm just wondering if there would be any real advantage of a 200mm f/3.5 prime over my current Tamron 70-300 zoom. Thoughts?

Have you ever done manual focus? It can be tricky to get used to. Optically, your Tamron should be better- a lot of reviews I see on the vivitar 3.5 show some bad CA (which can be fixed in post), and it has to be stopped down to 5.6 for decent clarity. If it was a series 1 vivitar, I'd say go for it, since they are better optically, but if it has to be taken apart and cleaned up, and you need to buy an adapter, I would stick with what you have.

Yes, I have several manual focus lenses (not in my sig). I appreciate your feedback. I think I'll stay away from this one.

I had that lens, recently gifted it to a friend. It's a pretty solid performer, didn't have any issues with CA on mine. I only gave mine away because my Vivitar S1 70-210 is f/4 at the tele end, so I didn't feel the need to keep it around. I'll post a few samples from it on my 6D tonight and maybe some from my friend's d800 if he'll link them for me.

As long as the "fuzz" isn't fungus, for 10 bucks, I'd buy it just to put on my shelf.

Just looks like lint.

Here is one from the Vivitar 200mm f/3.5 M42

Sunrise from home @f5.6 I think

Probably fungus. If you ever wanted to tear apart & play with a lens, for $10 why not? Fungus can be cleaned, but I wouldn't keep it near any other lenses until you do clean it.