How important is photometry in photography?

Photometry is very important in photography. The required exposure luminous flux is mainly determined by photometry, which is the premise to determine whether a photo can be accurately exposed and accurately restore the relationship between light and shade of the scene. Without photometry, we can't know how to get the right luminous flux combination and reasonable exposure. Without photometry, we can only explore, estimate and guess the exposure combination. Faced with failure at any time, photography has become a difficult problem that cannot be effectively controlled.