I currently have a 17-35 2.8-4 Di Tamron and a 24-85 G 3.5-4.5 Nikon and use them on a D100. I am thinking about a lens upgrade and have been comparing my lenses where they overlap. The Nikon has more contrast but the Tamron gives me more detail and I can add contrast. In fact the Tamron gives me detail in areas where the Nikon gives me dark shadows. With the Tamron lens I can add contrast and end up with more detail in the shadows. Also the leaves on distant trees are more like green blobs with the Nikon lens but are more like individual leaves with the Tamron lens. My comparisons have been at 28 and 30 mm. I looked at the focal lengths that I used for 300 photos and 90% were between 17 and 50 mm. 50% were 17 to 24 mm and 40% were spread pretty evenly from 28 to 50 mm with the last 10% ranging from 52 to 400 mm. The simple answer here is to buy a 17-55 Nikon, but I am wondering if that lens will give me the the best detail that I can get through it's zoom range. If a 17 to 35 will give me better detail in that range I will stick with it and consider "The Beast" 28-70 2.8 AF-s Nikon. If I saw convincing evidence that it is better than what I have through it's range I would also consider the 28-75 2.8 Di Tamron. Does anybody have any thoughts on this? Sorry this was so long.