Quote Originally Posted by jsimoespedro View Post
But what happens if:

1) Expose at 100, develop at 200.
2) Expose at 100, develop at 50.

vs.

3) box speed 100, expose at 200, develop at 200.
4) box speed 100, expose at 50, develop at 50
1) Your negative will be relatively "contrasty" - This is like (but not exactly) N+1
2) Your negative will be relatively "flat" - This is like (but not exactly) N-1
3) This is the definition of "push one stop"
4) This is the definition of "pull one stop"

Push/Pull and N+, N, N- development are different vocabulary used to describe exactly the same thing... But importantly to achieve different goals.

I am oversimplifying to make a dramatization, don't anyone who shoots in the dark take this as a character attack. When you have to shoot in the dark you have to push...

Most people "push" film to get a faster shutter speed in a dark bar, in careless or sloppy shooting conditions under pressure where you can't control light. The idea is to get a negative that you can use from an otherwise hopeless situation.

The Zone System is used to give a negative of a carefully measured and exposed scene, just the right amount of development so that it gives the best quality negative.