I actually saw the film in theaters when it was released. In 1973, no one debated or even noticed the tonal, gradient values like we do today such as those represented in a lot of David Fincher films, for example.
IMHO, Roizman saved The Exorcist from another disaster like The French Connection transfer that Friedkin ruled over. TFC looks like shit and Friedkin claims “it's his work.” He's right. It belongs to him and he can watch it all by himself. Never tinker with an intentionally gritty, grainy, raw film like TFC.
The Exorcist, however, is brilliant thanks to Roizman.
Father B