I have a D90 and I'm currently using the AF-S VR Zoom-Nikkor 70-300mm f/4.5-5.6G IF-ED lens. I'm taking some pretty good bird pictures but I want to make a significant upgrade. I have a friend that's using a AF-S Nikkor 400mm f/2.8G. I think he paid around $9,000 for his lens but I was hoping to spend less. I was also wanting a lighter weight lens. I'm new to DSLR photography so comparing the technical specifications one lens to another is confusing at best. I'm looking at the AF-S VR Nikkor 200mm f/2G lens as an option. Anyone using this lens for photographing birds? Any reqrets?