It is hard to know where photography’s characteristic of realism starts and ends in objectivity. It has been hammered again and again, this fervent debate of the photograph - art or science?
If one category of photography were to be the most accurate translation of reality, I would offer up color positive film. I am not saying this matters in the slightest. However, when using transparencies a photographer’s creative decisions can remain mainly in-camera. The film itself, once developed, can be simply displayed on a lightbox or projected, and further manipulations and further abstractions of the image are rendered unnecessary.