Well I have just got the lens and was playing around with it in NYC today. So not really a good test of its qualities. I did have the 16-80 for awhile and two things for sure, the tamron has a better F stop, so there is that. And also, from the reviews I have read, apparently the tamron does generally better in the sharpness department throughout the zoom range. I really couldn’t care about the lack of aperture ring. People here seem to think that is just so important, not sure why, The XT 5 realizes that the tamron is on the camera, and the front wheel controls the aperture. No big deal and quite easy really. And they say, oh, I like an aperture ring so I can tell what my F stop is by looking at the camera, I tend to keep my lens at its wide open setting and with the tamron, 2.8 is perfectly adequate for sufficient sharpness, so that problem is solved.
I am always amazed by reviews that nitpick about truly minuscule BS stuff. As if they actually need to find something wrong or they think that they arent giving a good review. It is like the pixel peepers here who look at a posted photo and want to examine the far corners at 300% and are worried about the lack of detail in those corners. As if a photo should not be taken as a whole for its composition, and lighting.
Anyway, sorry to express a tangential thought. Bottom line from what I can tell, the tamron seems to work great, I took a bunch of photos at a dog park, It handled it well with the XT5 set to subject AF animal.
