I can't believe how well this lens performs on my D7100 and D300s. I've been lugging big prime lenses with tripods, but old arm injuries make this more and more painful. Nor can I afford the 8K image stabilized 500 and 600mm primes. But, I sold my 300mm 2.8 VR and the AFS non-VR sits unused. I'm curious to see how IQ compares to the 80-400VR-G (AFS), but I just don't feel the need to right now, and don't feel like spending 2,400 or so on another lens, when this one works perfectly well. I will eventually, but as a "I only use primes" kinda guy, I can't believe this Tamron, made in China, is as good as it is. I have not yet tried the VR version of the 300mm f4, but for many years used the 300mm f4 non-vr (always with TC 1.4x IIe) and loved that setup. But the 600mm reach of the Tamron is legit sharp on my copy, and the VC really works well. This is not a low light lens, but does surprisingly well in low light, considering app is 6.3. Maybe not quite as contrasty in color as Nikon glass, but that is more likely a factor of my poor shot selection vs lens quality.
Anyway, I highly recommend this lens for birding Nikon users. Its going to give Nikon