Watching North by Northwest at home last night (for the umpteenth time--it's a great favorite of ours) and suddenly noticed all the diagonals in the shots--from the opening credits, which feature the exposed steel grid of a modern office building on the bias, to scenes of Cary Grant clambering among the unusually angled support stilts of an ultramodern house near the Mt. Rushmore national monument in South Dakota.
I wondered why that was, throughout the movie, and was still wondering this morning, so I decided to try a Google search.
The "D'oh" came as I was typing in the words "north by northwest diagonals" into the Google search box.
At least I didn't have to see the search results before I had my "aha." And this is not to say that there aren't all sorts of other good reasons to shoot on the diagonal--adding to the sense of action, of things being off-kilter, and so forth.
But, clearly, N-NW is a diagonal.