Posted 27 November 2012 - 23:37
These images do show the strong and the weak points of the 120 Medical.
The strong points are excellent sharpness when the lens is stopped well down, better in fact than the behaviour of most Micro-Nikkors. The lens draws colours vividly but not deeply saturated so the overall outcome is pleasing to the eye.
The weak points spring from the targeted design, as this lens *never* was intended to be used for 3-D subjects for which the bokeh had importance on the outcome. Thus, it has a very harsh and unforgiving rendering of the out-of-focus background and details hidden there. Contributing to this issue is the mechanical design of the lens that couples aperture with focusing. You cannot treat aperture independently. Usually one ends up with a lens stopped almost all the way down, in particular for close subjects. Thus separation of subject might suffer due to the extended depth of field.
Since I found these caveats too restrictive, I modified my Medical Nikkors so the aperture could be set independently, by decoupling the internal linkage (be warned: this requires in-depth surgery so is not for the faint of heart). Plus you have no way of actually setting the aperture unless a "G"-type CPU chip is added to the lens. So my Medical Nikkors promptly got their CPU as well.
Bjørn