On any movie set, the cinematographer often has a symbiotic relationship with the director — Janusz Kaminski, who just shot The Post, has been working with Steven Spielberg for 25 years. But that doesn’t mean these pros don’t have a lot of opinions of their own, as was clear when Kaminski, 58, met to talk shop with Blade Runner 2049’s Roger Deakins, 68; Dunkirk’s Hoyte Van Hoytema, 46; Mudbound’s Rachel Morrison, 39; The Shape of Water’s Dan Laustsen, 63; and Suburbicon and Roman J. Israel, Esq.’s Robert Elswit, 67. Whether revealing some of the happy accidents that resulted in unexpected and hauntingly beautiful images or bemoaning the challenges of filming in the pouring rain, they share a common experience and language. “It’s so much about chemistry,” says Van Hoytema, who…