Summary: When I rated this lens I factored in the photo quality AND the service provided by Tamron. I use it on a Nikon D800 and find the sharpness acceptable. What I don't find acceptable is the way Tamron handles their warranty. I have had this lens for 5 years. The warranty is 6 years. When I tried to use it in movie mode, it would not focus in live view. Tamron said it needs to be serviced to correct the problem.
Summary: I just got the lens yesterday from the port agent where i address the package because i work on the Cruise Ship, the lens is very disappointing because of its bad quality, blurred and soft image. i really want to send this lens back and get a Sigma 18-250mm for my pentax, if amazon will only give this chance i will not stop buying things from your website, amazon knows how much money i already spent in their site and i am one of their good customer.
Excerpt: We have two of these lenses and both have exactly the same defect: they shut down at long focal lengths. Tamron wants to charge 140 dollars for each lens to remove the problem, even though the problem is obviously a defect in the lens and not due to our usage. Tamron USA says that is their orders from japan and they can't do anything about it. And are not at all sympathetic, pleasant, helpful, or even apologetic.
Summary: We have two of these lenses. Both shut down and stop working at long focal lengths. Tamron wants to charge 140 dollars to fix each one, even though the fact that both have the same defect shows it is their fault. Forget Tamron. They do not stand behind their products and the product is a mess to use.
Excerpt: Bought this lens along with Sony a33 from B@H. It really has a good picture quality, great macro capabilities, nice bokeh, BUT... Autofocus simply didn't work, especially on a moving object. It would go back and force with irritating noise scared non only birds but horses away from me but will never let you make a shot. No use for sport or nature photography.
Excerpt: I was looking forward to having a nice walk-around or "vacation" lens for my new Sony Alpha 580 camera. I was extremely disappointed in the quality of this lens. It's being returned. I don't know if I got a bad lens, or if this is the normal quality of the lens. It was very "soft" throughout. The extreme zoom end was blurry, the close ups of flowers were blurry and not in sharp focus. There was nothing I can say I liked about this lens except for the zoom range.