Here's where I'm at with the Tammy so far.Very pleased with the results right out of the box and I normally AF fine tune things to achieve happiness. I may do this one as well but happy as is so far. To put that into perspective I tried to buy a second one today so my wife and I can have one each as the fist fight we had over this one last night was a messy affair, albeit she only just beat me 
It might sound a little decadent to be getting a second unit but in fairness we've been waiting for this thing to be available for six or more months and always intended to get a pair once we'd tried the first to see how it performed. So far I've failed in my mission as even the place that showed stock in the UK was actually sold out. I've put my name down.
The other debate I've been involved in over the past year or more was how does my Nikon TC-20E III perform at 400mm on the Nikon 70-200 2.8 VRII. I've previously posted images from that combo showing just how sharp it can be, however I've never been happy with the consistency of the results. Now that could be me, my camera bodies, my lens or my TC. Today I did a quick test today on a tripod with MUP comparing the Tammy at 400m (5.6, well 6.0 and F8) against the 70-200 TC combo at 5.6 and F8. In the first test the Tammy won hands down to my eye. I then tried a different D7100, with a different 70-200 but the same TC. In fairness it was an improvement but still not as good as the Tammy. Both the 70-200/D7100 combos had also previously been AF fine tuned. The Nikon combo also showed noticeable CA against a light bachground!!
The other thing I did was take the Tammy and Nikon combos outside and take a couple of snapshots from my driveway handheld. Again the VC on the Tammy easily beat the Nikon combo.
These tests are not scientific but to me they tell the truth about what I'll see in actual use, particularly the outdoor shots, but YMMV. If you have the TC/70-200 combo and get good results that's great and don't rush to change it, but for me the TC-20E is about to be sold so I can get fantastic results from the bare 70-200 and great images from the Tammy at the longer focal lengths.
One final point. The 70-200 and TC went back to Nikon shortly after I bought them as I wasn't happy, so they should be a good example.
It might sound a little decadent to be getting a second unit but in fairness we've been waiting for this thing to be available for six or more months and always intended to get a pair once we'd tried the first to see how it performed. So far I've failed in my mission as even the place that showed stock in the UK was actually sold out. I've put my name down.
The other debate I've been involved in over the past year or more was how does my Nikon TC-20E III perform at 400mm on the Nikon 70-200 2.8 VRII. I've previously posted images from that combo showing just how sharp it can be, however I've never been happy with the consistency of the results. Now that could be me, my camera bodies, my lens or my TC. Today I did a quick test today on a tripod with MUP comparing the Tammy at 400m (5.6, well 6.0 and F8) against the 70-200 TC combo at 5.6 and F8. In the first test the Tammy won hands down to my eye. I then tried a different D7100, with a different 70-200 but the same TC. In fairness it was an improvement but still not as good as the Tammy. Both the 70-200/D7100 combos had also previously been AF fine tuned. The Nikon combo also showed noticeable CA against a light bachground!!
The other thing I did was take the Tammy and Nikon combos outside and take a couple of snapshots from my driveway handheld. Again the VC on the Tammy easily beat the Nikon combo.
These tests are not scientific but to me they tell the truth about what I'll see in actual use, particularly the outdoor shots, but YMMV. If you have the TC/70-200 combo and get good results that's great and don't rush to change it, but for me the TC-20E is about to be sold so I can get fantastic results from the bare 70-200 and great images from the Tammy at the longer focal lengths.
One final point. The 70-200 and TC went back to Nikon shortly after I bought them as I wasn't happy, so they should be a good example.