> Here are very preliminary plots in lp/mm of a Rodenstock Digaron W 40 mm and a Zeiss 25/2, both images converted in LR4 without sharpening.
Thank you, Erik. Obviously there is no weight to save on the wide angles. But they could not be adapted anyway. The shortest that could would be the Digitar 72. Flange to focal distance 68.4 mm, of which the Nikon would take 46.5, leaving 21.9 mm for a helicoid (17-34mm) + adapter rings. Here the weight difference would be significant, about 220 grams vs. 525 for the Sigma 70mm. From f=100 mm and up, a Zörk or Mirex shift adapter might be squeezed in.