I am a new member to Nikon. I have a Nikon 18-35mm for my architectural assigment shooting and I found it just have too much distortion at the wide end and quite disapointed to the pictures. I understand that the Nikon 17-35mm F2.8 has a lot lower distortion but its $1700, man! Talking about I just invested in the D700, 24-70mm f2.8, 70-200 VR and a new sigma 50mm f1.4. To get another $1700 lens is killing me (even used one cost $1400-1500...). I thought about switch to a used 20-35mm f2.8 but its almost stupid to do that because I have already owned a 24-70mm f2.8 Its such small different between 20mm and 24mm. And also, I do need wider for my architectural shooting. Here I found the Tamron 17-35mm. It has pretty good reviews online. Its affortable. From some web site's reviews, look like it has less distortion than the Nikon 18-35mm (but not as good as the 17-35mm f2.8). I am wondering if anyone have experience on the Tamron. How is it compare to the Nikon 18-35mm? How is the build quality? How is focus speed?