When I first started out, I wasn't able to afford Canon's FD lenses, so I opted to read as many reviews as possible on after-market lenses, to see which would suit my needs.
Ended up choosing Tamron as my brand of choice - their Adaptal-2 mount system was great and they had a great selection that suited my requirements as a sports photographer. Apart from the 50mm f1.4 that came with my used A1 and a 135mm f2.8 that I purchased duty free, every other lens I owned for the next 20 years, was from their stable:
- 17mm f3.5 (paid approx $395 used) - as others have said, very little between this one and the Tokina version. I've used both, but the Tamron was always the favourite;
- 28mm f2.5 (paid approx $195 used) - wanted the 24 but was out of my price range new and rarely appeared used. Pin sharp and exceptional value for the money spent;
- 90mm f2.5 (paid approx $295 used) - the older version that needed you to purchase the 1:1 extension tube. Was lovely and a great portrait lens too;
- 180mm f2.5 (paid approx $1.5k new) - magnificent lens that matched perfectly with their 1.4x and 2x converters. Pin sharp, fast (and the leather case it came in was a nice touch too!);
- 300 f2.8 - (I paid approx $3.5k new) this was a monster lens that was so close to the Canon version it was scary. My cousin shot for the local newspaper, and had the Canon version and he swapped it out one day when we went shooting football. He was amazed by the clarity and sharpness - matched with his Canon 2x, it was one wild lens! It came in it's own lovely leather case, with a small screw-in rear filter holder and 1.4x converter as standard. (I even paid $200 for a Tamron front filter (112mm from memory), just to keep it protected.)
The last two were by far the largest purchases I had made (had to pay them off weekly), in my early years of photography. Sadly when I had to go to the dark side, I unloaded them at much less than I would have liked, (needed to change to EF quickly) work taking priority over sentiment.
I loved that 28mm so much I purchased another 5 years after unloading my original, (actually spent more on the EF Adaptal-2 mount than the actual lens!

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