This image also shows clearly the mild vignetting of the 70-300VR when shot side open. It occurs on all lenses, some much more than others. PTLens and other tools can deal with it, but that *will* add noise to your corners. So stopping down a bit can be prudent.
Same parameters for this test ... except for two changes: VR is off on both lenses (and the 18-200VR does much better on the tripod that way) and 160ISO instead of 2000ISO for yesterday's test (yes, that was a brain fart.) So this time we can see very subtle differences.
Note that I left out the Sigma 70-300 APO Macro as it is simply not a contender to me. I can find something redeeming in even my cheapest lenses, but not in that one. I have far too many great alternatives.And the results:
Overall, no contest at all. The 70-300VR returns excellent magnification, excellent contrast, and sure footed focusing (even in live view.) The only minor issue is some CA ....
On the other hand, the 18-200VR, while being surprisingly sharp, was less sure-footed in AF and has really poor magnification.It must be at 180mm or less as we get this close.
The prime's sharpness is destroyed by the Kenko 2x teleconverter.
And the Tamron cannot AF to save its life ... although it is very sharp and no CA.
So the Nikon wins and again, I cannot see a reason to use anything else. Am I convinced now? I suppose we'll see ... I'm betting that I have the 105mm 2.5 AIS with me just in case :-)