The Nikon 500mm rules @ f/32 in terms of actuance:
This might lead to a higher summed up score because DxO produces the score from data over the whole range. If this is NOT WEIGHTED with typical use scenarios ... this gives misleading scores while the measurements are correct AND helpful.
This might explain why Canons and Nikons 4/500 have the same scores - I would choose Canon's lens because it should deliver cleaner results @ f/4-f/8 - the typical f-stops I would use.
I'd like to ask where DxOMark states the Score is summed over the whole range...because instead, I read: "DxOMark Score corresponds to an optimal focal length/aperture combination. The score corresponds to the quantity of information that can be captured by the camera. Each focal length/aperture combination provides a numerical value. The highest value is the DxOMark Score.
". They're saying the score is based on the one best focal length/aperture combo. They indicate that right next to their Score, and for all three lenses that optimum is 500mm f/4.
Sorry, but I believe actuance at f/32 is irrelevant to the Scores, which are still BS...