I recently purchased a Tamron SP 24-70 2.8 G2 to use on my D610 and D7200. It is an upgrade from my Nikkor 24-85 3.5-4.5. After receiving the Tamron I ran it through a battery of focus checks and, in general found the AF to be pretty close. On a lens test chart it was a bit better than the Nikkor on the edges and about the same in the center (Tammy at 2.8, Nikkor wide open approx 4.0 at 70mm).
In a real world test, I imaged the trunk of a Live Oak tree in my yard with both lenses and at the same focal length and same aperture (f5.6 to f8) I have a very difficult time telling the two apart. I bring up the unprocessed nefs in LR's side by side comparison window (1:1 crop) and move around the images from center to top and corner and just don't see a noticeable difference.
My question is, should I? I had imagined the Tammy would be head and shoulders better than the Nikkor, but it's doesn't seem to be. I admit that I have not been unhappy with the Nikkor, with a little post processing, the images are really very clean. I was looking for a boost in sharpness, mainly for close portrait work. I really want to like the Tamron, but at present, I'm increasingly leaning toward returning it and sticking with the 24-85. I don't need the duplication and really don't want to stick with a $1200 dollar equivalent to a $500 lens. There are other focal lengths where I have gaps. Any suggestions? Other ways to test the two back to back that would give the Tammy a chance to impress me? Something?
Thanks in advance.