Photography is about light. No light; No photography.
A stunt favoured by cave tour guides is to turn off all the cavern lighting when the tour reaches the deepest point in the earth. People discover without light, they cannot see — nothing, nada, zilch. The world in an unlit cave is a black void. Encouraged to wave their hands in front of their faces, they cannot see their hands no matter how close to their faces they are waving them.
For many people on such tours, this is the first time in their lives they actually have "seen" total darkness. Total darkness is pretty rare. For this reason, to find a spot where no photography is possible you may have to head for some caves.
If you head for the hills at night, simply bring a tripod and you'll be fine — especially if you have learned to watch the light.
Take today's picture taken in a relatively dark restaurant. To grab a photo here demanded a careful reading of the available light. First, there was some light coming through a wall of windows some distance away. It was nice soft light but weak and made weaker by the time of day — dusk.
The lights on the walls offered a way to backlight some scenes to force subjects to pop free of the background. (So often, in these situations, dark hair simply disappears into the dark background making for ill defined subjects.)
|Even with most light coming from behind, I got a shot.|
I tried to time my picture taking to a moment when both waitress and customer were still. When they were going over the menu, I saw my opportunity. I shot lots, and lots didn't work. Camera and/or subject movement ruined a number of shots. (I used a similar approach to capturing the interaction between the Bud Light Lime crew and a couple in a London, Ontario restaurant.)
Personally, I don't like straight on flash photography. Sometimes one has no choice but to fall back on one's flash for light, but if you can accept the coarseness of high ISO settings and the loss of a fair number of shots to movement problems, learn to watch the light and you will grab some nice unguarded moments.