We finally got two copies of the new Tammy today and I played with it for a hour or so shooting several hundred images (at higher ISO 800-1600) of bar-codes and co-workers.
My initial impression on the Tamron 70-300mm VC USD is (using the D700 and D300 camera bodies):
1) stablizer (VC) is far superior to Nikon's VR when hand holding at 300mm: far more keepers with it than the Nikon with our store's lighting when shooting subjects/products/numbers/bar-codes with distinct sharp letters. This was demonstrated consistently back/forth between both Tamron and Nikon lenses at 300mm (Nikon VR on "normal" mode).
2) The Nikon is faster to initially focus and track (both in AF-S and AF-C focus modes) with "LOCK-ON" on OFF on both bodies. The Nikon "twitches"refocuses the lens faster both at 70 and 300mm extremes vs. the Tamron lens. There is a slight delay when shifting from one focal plane to another with the Tamron (hence tracking servo speed). With the co-worker walking semi-fast towards the camera (AF-C mode), ALL images however were sharp when reviewed (100% on camera's LCD unfortunately).
3) sharpness and contrast is far superior with the Tamron: color boldness and micro-contrast with the lens seemed to just "POP" when shooting in these lower light conditions. It's unfortunate I've not had a chance to shoot in good/bright light (hence the slower apreture lens) to test it's outdoor/bright light performance.
The sharpness at wide open apretures were consistently sharper and bolder on the Tamron (to be expected with newer and more refined coatings and glass-manufacturing processes: the Nikon is a few years older than the newly released Tamron).
Sharpenss and contrast may have also been attributed to the Tamron's superior VC system, however with repeated shots after shot (with sufficient shutter speeds), it proved to be a real winner.

此国外人士对Nikon AF-S 70-300mm VR vs Tamron SP70-300 VC USD用Nikon D700和D300机身，在三方面进行了试拍对比，得出其体验结论（简言之）：
1.防抖   - Tamron 胜 Nikon
2.AF聚焦 - Nikon 胜 Tamron
3.分辨率 - 技术今胜昔，待几年后Nikon的这支镜头更新版发布时，定会胜Tamron这支镜头的。现在暂时落后。  
仅供参考而已。估计没几个人（不会超过3.27%）会相信这个对比体验的。在※※，“原厂”两个字就胜过了一切事实。3.27%是什么？点击下列链接，便知。
http://news.xinhuanet.com/politics/2010-11/25/c_12816366.htm

不过，若http://www.dpreview.com 和 http://www.photozone.de 发布评测结果，将更具参考价值。

[Jupter 编辑于 2010-12-05 23:28]