Test a lens not optimized for close up (Zeiss ZF 50/1.4 Planar) using small test charts (where it’s at its worst), and what do you have? A good idea of how the lens performs under those conditions. But not much of an idea of what kinds of images it will make under other conditions (other focusing distances, severe backlighting, ability to hold highlight and shadow detail, etc).
What am I referring to? Reviews like this one at slrgear.com. A good starting point? Yes, all sorts of hints are available from the test data for exploration with field shots. I urge readers to understand the by-the-numbers reviews at slrgear.com (and dpreview.com) in that context; there are many outstanding lenses with unique characteristics that do not acquit themselves well on test charts. A good example is the highly sought-after NOCT-Nikkor. A future article will show just how “bad” it is compared to the Voigtlander 58/1.4—yet its rendering capabilities are unique.
The Zeiss ZF lenses are a mixed bag; all are superb, but in different ways. Some, like the 100/2 Makro-Planar, can hardly be criticized on a test chart. Others, like the 25/2.8 Distagon, look pretty darn bad on a test chart, but are simply marvelous used at farther distances and have highly unusual rendering quality for extreme close-ups.