There is some misunderstanding in some of the replies so far.
I think I have to give some additional information about my tests.
First, my tests were aimed to evaluate real life images and I did not intend to measure absolute resolution figures. I use lenses to take pictures and not to get numbers.
Being the happy owner of the three lenses I tested (105 VR, 85 PC & 100/2 ZF) I wished to share my "subjective" evaluations about those lenses with the many people who visit my website. I put 100% crops to substantiate my subjective evaluations and to ask people different opinions if they feel that my conclusions were not sound.
I scrutinized the NEF files and I draw my conclusions on the IQ of the three lenses by looking at files on my calibrated LaCie monitor. My long lasting experience as Nikon user (I've used tens of Nikkor lenses in my life, and all 105 Nikkor lenses but 105 DC) and editor of photographic magazines helped me in evaluating as critically as possible my findings.
Due to obvious reasons, I had to publish in my webpage the jpegs of the files obtained by using 105 VR, 85 PC and 100/2.
The jpegs were obtained by NEF files using NX2 (quality 100). The differences in IQ were a little bit flattened by jpeg conversion.
According to many shots I've analyzed using different apertures and different magnifications (from 1:2 to infinity), I am convinced that the Zeiss 100/2 produces better images than 105 VR. The images produced by the Zeiss are "cleaner", with a biting clarity that the 105 VR is not able to produce (this doesn't mean that the 105 VR cannot produce excellent 14 in, wide prints).
And the 85 PC is optically better than 105 VR and almost as good as 100/2 ZF (which is a f/2 lens!).
When we are comparing first class lenses, we are not disputing if the Zeiss differences are easily detectable in a 20 inch wide print or not. Nobody said that, and I guess Leonard Shepherd has never compared two 20 inch wide prints of the same subject, taken with the same camera and with 100/2 ZF and 105 VR.
He "supposed" there is no visible difference.
But let's assume he's right. This does demonstrate nothing.
We/he forgot that I wished to compare three first-class macro lenses.
As always, to manufacture a 1 stop faster macro lens with better performance than a very good macro lens (like 105 VR) implies significantly higher costs.
If we don't think these costs are justified, well this means that the faster and more expensive lens is not the one we need.
Now, it is clear that
f/2 aperture is a plus for a medium telephoto lens .
It's important for portraiture, otherwise why Nikon and Canon produced and continue producing f/2 portrait lenses (105 DC, 135 DC, EF 100/2, EF-L 135/2) ??
In fact, I bought the ZF 100/2 not to replace my 105 VR, but to replace my AIS 105/1.8 ...
It's also clear that f/2 aperture allows getting a brighter image in the viewfinder, and
a brighter image in the viewfinder is important when focusing carefully a macro picture . Isn't it?
It's also clear that most of the times we use MF in macro photography. Right?
Well, a state-of-the-art focusing ring helps a lot. I find that using LV and MF with my (faster) 100/2 ZF is much better than with my 105 VR.
The ZF is 1:2. And so what?
you can get 1:1 with PN-11 (with the additional bonus of a tripod collar!) or you can get 1:1.3 with a Canon 500D close-up filter.
Therefore, the lack of 1:1 doesn't mean that you can't get it
in a easy and even more comfortable way (thanks to the tripod collar of PN-11) .
Last but not least, a MF 100/2 macro lens built like a tank will last many many years maintaining a constant performance. I'm not sure a AFS VR lens will last for a life without any need of service ...
Best,
Riccardo
).
