Below you see the upper part of each image (red crop). Zoom lenses were tested at 20 mm.
Spezifications: Canon EOS 3 or Pentax MZ-M, Fuji Sensia 100.

Peter H. Pak from the USA kindly provided me a full frame image of a garage door taken with the Leica Elmarit 2.8/19 II. Here you can see the same crop as in the images above.

Distortion of zoom lenses depends on the focal length. Here you find some more detailed results of the wide end of the three zoom lenses.