Sigma 17-50 OS or Tamron 70-300 VC?

[PaulWog]

I think there are four really good options in the semi-affordable range:
Tamron 150-600
Sigma 150-600 Contemporary
Nikon 200-500
Sigma 150-600 Sport

I think all four lenses have their merits.

The 70-300 VC should be good enough for birding though. If it truly is a bad copy, that's one thing, but based on reviews it should perform as good or better than the Nikon 70-300 VR, which was between adequate and decent.

 

[gckless]

Well, I have the Sigma 17-50mm, and I like it. But it's quite a different focal length range we're talking about here. What about the Nikon 70-300mm VR?

My suggestion is to rent a high-dollar telephoto lens and see if it truly is the lens or if it's your technique/body/etc. Also maybe have someone at a local camera shop try out your lens.