Just for variety the same test was done at 200/4.0. Here, with no filter, the average RGB value of the center of the dark box is 41,41,37. Again this is the base contrast of the lens for this target. This seems to indicate the lens is a bit more contrasty at the long end, but perhaps this is also because the lightbox doesn't quite fill the frame as much as in the 70mm shots.

Just for variety the same test was done at 200/4.0. Here, with no filter, the average RGB value of the center of the dark box is 41,41,37. Again this is the base contrast of the lens for this target. This seems to indicate the lens is a bit more contrasty at the long end, but perhaps this is also because the lightbox doesn't quite fill the frame as much as in the 70mm shots.