What is the proper exposure for a photo? The one that looks the best.
For the most part we generally go for the middle range, getting that histogram hump in the middle rather than at the ends. If our image is too dark we want to lighten it; too light and we darken it.
With film, it is better to over expose a little rather than under expose. If there is there is too little exposure, there is not enough emulsion and you’ll get crumby prints. With digital, under exposing a little is better. If you blow out pixels, you’ll never be able to pull out texture or color from them.
But that’s not the topic. What is the proper exposure?
Ansel Adams was famous for having a wide range of exposures in his images from black black to bright white (tonal range).
That’s not a bad goal. Tonal range gives your photo more body, more visual interest. It stimulates the eye more than a flat, low contrast image.
So that means some areas are over exposed and some are under exposed. That’s great as long as it looks the best.