is photography the process of making pictures by means of the action of light?

Answer 1

Pretty much, you have the historgram that tells you both in digital and film cameras if you have enough light shining through the lens to make sure your photograph isnt over or underexposed. The way the light comes in lays a huge factor in taking good photos. You could dismiss the light, and your photos wouldnt turn out well, but with slr cameras it is what you depend on. If you ever watch the bar to the side of the film slr, it fluctutates depending on your position to a light or the sun. If you point it right at the light, it goes above the plus sign on the meter, and that would make your photos overexposed and bright because the lens is allowing all of that light to absorb into the body and mechanisms. If you turn your back and focus on a dark object with little light the meter follows the minus sign, meaning underexposure.

Answer 2

Unless you prefer the picture of the black cat in the coal cellar at midnight, then I guess its the action of no light.

Answer 3

Yes. Basically.