The Tammy wasn't a bad lens at anything but 2.8 - maybe 3.5 at any length, at least not my copy IMO. Also, IMO if a lens has 2.8 it should be at least somewhat usable at 2.8. Overall, I just couldn't accept this lens for some reason and avoided using it, could be because I once owned the Canon 17-55mm.

I absolutely love my Sigma 85mm but if I owned the Canon 85mm 1.2 L II previously, I probably wouldn't like it as much either but I didn't, I owned the 1.8 and this is a great improvement.

The Sigma 50mm was also a great improvement over my 50mm 1.4 IQ-wise but it had some occaisional backfocusing issues I noticed and I realized I really didn't need a 50mm prime all that much and the 1.8 II would suit me just fine and it does. With the extra $, I was able to get a number of other things I needed more.

If I get a good copy of the Sigma 17-50mm, I know I will be more than thrilled! Sigma makes good lens IMO but getting a good copy is the key! People that have the Siggy 30mm love it as you can tell on the used market ...they are extremely hard to get ahold of second-hand. I was looking for quite awhile before I bought the Canon 50mm 1.8.

From what I have seen and read about the Sigma 17-50mm, it will be worth sending back a time or two if the first copy doesn't work out and just wait until a good copy comes through for me.