Quote Originally Posted by Terry Christian View Post
Extending (or shortening) development times by as much as 150%, 200%, etc., is essentially pushing (or pulling) the film. With Zone System N+ or N- development, the goal is not to push or pull, but to gently tweak the contrast level to fit it into the range the film or paper can hold.
Yup, in addition to testing to find the actual development needed for your film/developer combo, the film needs to be exposed in the first place with the intention of expansion. Just over cooking film for some arbitrarily stated time doesn't necessarily get you N+ anything but a bullet proof negative.