TooManyShots wrote in post #18020992
I agree...the VC is mah... Some says the VC can auto detect if you are panning or not. In my experiences, it depends....

Not just panning but if you move around and to track your subjects, the VC appears to be struggling to follow your movements.
I checked up on the Tamron UK site regarding the firmware update for the VC "issue". This suggests that the update simply switches off the VC while panning/moving the lens with the VC switched on. Saying that they do seem to be deliberately vague with the comments. On the shorter focal length zooms the 70-200 f/2.8 VC and I think the 70-300 VC, the system not only auto detects deliberate large scale movements that would be consistent with panning, it then switches to a "Mode 2" style of function. In the rather long phone conversation I had with a Tamron rep about the problem after I had rented the lens and lost a lot of images thanks to the feedback problem, as I was shooting at 1/160 over the full range of focal lengths at an airshow, and got bad results even at mid ranges of the zoom, around 300mm where I often shoot an unstabilised lens. The explanation that I got for having no panning mode was that at the magnification involved in shooting at 600mm Tamron was unable to get the auto switching system used on the other lenses to work while panning. This I was told was a hardware issue, and unlikely to be fixed without a completely new VC system.
Having used the Tamron as well as the Canon 100-400 ver 1, I have to say that IMO the Sigma 150-600 C is the all round best of those three lenses, especially since the latest firmware update. I have had my Sigma since last October. I admit I do really need as much focal length as possible, and could really do with 900mm, since I still often have to crop my 50D by 1.5× to get a good composition. With the 100-400 I still only felt OK cropping by the same proportion so was still coming up very short. If I had a f/8 AF capable body there is the option of the 1.4× Extender, but you can also do that trick with the Sigma, and they have now got a new converter that is supposed to be matched specifically to the two 150-600's and the 120-300 f/2.8.
Alan