UPDATE: There was a problem with the lens and I had to send it to Tamron for warranty repair. GREAT customer service experience. The repair was quick. I sent it to them with UPS slow shipping and got it back 10 days later. Better experience than Nikon customer service. I am very happy that I bought this lens! The autofocus with it on my D750 is quiet and fast. It's so fast it's hard to tell if it's even focused! As if nothing had happened. Now this is my fastest focusing lens. I find that the image quality is actually slightly better than the Nikon/Canon versions. be extremely durable (i.e. you can beat it up), retain its value (for a well-known brand), and have perfect and top-notch autofocus speed (e.g. Sport) because Tamron can be fast, but still a bit slower than Nikon/Canon -Lenses. Otherwise, the Tamron is just as good, if not better, in every other category. Some comments: - I'm glad to have this series for landscapes; I no longer have to carry prime lenses and telephoto lenses with me. Yes, the Tamron is heavy and a bit big, but now I have 2 lenses fewer and a GREAT range for landscapes (70-200 is my favorite range to shoot) in one lens. β My first weekend photographing landscapes with it (sunrises, mountains, fog, valleys, trees, etc.) and not a single picture was bad. They were all perfectly focused and marked. The same cannot be said for my Sigma 150-500, which keeps overshooting, even by 150mm. Again an incredible picture quality. Neat - Focus hasn't let me down yet! - Construction: build feels solid; It's a bit "plasticier" than Nikon/Canon, but as long as you don't insult it, it feels great. Durability: Seems durable, but I haven't had it very long. The time will show.