This isn't a scientific test, but may assist those who are considering buying a Tamron lens. Note the caption indicating the camera settings and focal length beneath each shot. I attempted to take a similar picture with each of the following lenses as a means of comparison: 70-300mm, 18-250mm, and the new 28-300mm. Each composition proceeds in that lens order. The focal length and aperture aren't always exactly the same, but I hope these shots prove helpful nonetheless. Note that the originals can be downloaded for pixel-peeping.