The 85mm f/2.8D PC Micro Nikkor
by
Roger Eritja
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RESOLVING POWER
The resolving powers were compared
using 5 Fotowand resolution targets over a 60x90cm (23.6x35.4")
blackboard. Lenses were mounted on a Nikon F4, film was Fujichrome
Velvia 50. This test is only indicative because it was not
performed at an optical lab and with a brand new out-of-the
box 105mm Micro Nikkor for the comparison, but with our own
working sample. No absolute measurement is hence given, but
a comparison between curves of the optics.
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Blackboard
with 5 targets for resolution tests
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A series of three images was shot
at each aperture for each lens. Reading of results was made
directly on the slide film, backlit, with a binocular microscope
at 60X, selecting the best value of the three series for each
lens. For the sake of brevity only the center images were
processed, notwithstanding the fact that the relative behavior
on the outside images was equivalent.
The results confirm what intuitively suspected, the resolving
power of the 85mm PC is very high and surpasses the 105mm
Micro Nikkor at all apertures, which is a superb lens.
Results also confirm the degrading effect of extreme closed-down
apertures, typical of the macro lenses. In practice, the last
two apertures should be avoided unless an emergency.
Showing such degrading, the images
that follow (below) are enlargements of the center images
of the resolution targets at f/8 (at left) and at f/45 (at
right) for the 85mm PC.
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