So I just went to Abel Cinetech today to try out the FS100, and they had a Sony 28-75mm F/2.8 SAM lens attached to it for demo purposes. I have been debating whether to get the Tamron 17-50mm or the SAL-1650 for my FS100 and was recommended to get the SAL-1650 because of build quality. However, I was not overly impressed with the build quality of the SAM lens that I tested. What turned me off the most was the zoom ring which felt really stiff. I am going to try and find a store that sells both lenses and see how they compare, but I am pretty sure they won't let me take them out of the store to do tests. I tried looking into renting these two lenses, but I cannot find a place that rents the SAL-1650 at the moment because it is too new. I was just wondering if anybody had experiences with both of these lenses and could compare the two. I am sure that both will do a good job. I'm just wondering if the added expense of the Sony SAL-1650 is worth it or not.