The film is not made more sensitive to light by pushing. Sensitivity is a property of the film. Pushing is simply overdevelopment in attempt to bring out whatever shadow detail was recorded by the film.
Originally Posted by wy2l
There is a difference between an emulsion's sensitivity to light and film speed. Sensitivity is a property of the emulsion. Film speed is based on the amount of exposure required to produce a specific set of densities under a standardized development procedure. Exposure index is a "personal" film speed based on subjective preferences and varying conditions.
Some references which may help:
ISO and Film Speed
Pay particular attention to point 2d regarding pushing
Pushing Refer to page 18 "All about pushing..."
Last edited by Michael R 1974; 07-12-2013 at 10:31 AM. Click to view previous post history.