I now have 3 tamron lenses... 2 I'm very happy with, the other, I am in the process of evaluating so no firm opinions yet. The two I like, I'll post pics, the 18-200 I'll post some pics later.
first, the 28-75:
Camera: Pentax K10D
Exposure: 0.013 sec (1/80)
Aperture: f/2.8
Focal Length: 55 mm
ISO Speed: 100
Camera: Pentax K10D
Exposure: 0.017 sec (1/60)
Aperture: f/3.2
Focal Length: 28 mm
ISO Speed: 100
Camera: Pentax K10D
Exposure: 0.006 sec (1/160)
Aperture: f/9
Focal Length: 28 mm
ISO Speed: 200
and then there is the 70-300... pictures take a bit more work to deal with ca, but not too much to eliminate the positives. Every time I use it, I always end up thinking, "I can't believe this thing only cost $130!"
Camera: Pentax K10D
Exposure: 0.006 sec (1/160)
Aperture: f/11
Focal Length: 300 mm
ISO Speed: 100
Camera: Pentax K10D
Exposure: 0.004 sec (1/250)
Aperture: f/5
Focal Length: 90 mm
ISO Speed: 200
Camera: Pentax K10D
Exposure: 0.002 sec (1/640)
Aperture: f/10
Focal Length: 240 mm
ISO Speed: 400