What push processing really does
DarkroomIt does not add sensitivity. It moves contrast.
The misconception
Pushing does not make film more sensitive. The exposure is what it is; extended development amplifies the mid-tones and highlights that did record, while shadows that recorded nothing stay empty.
What you actually get
Higher contrast, more visible grain, and compressed shadow detail. Sometimes that is exactly the look you want. Often it is the price of shooting in light that was too low.
| Push | Typical dev increase | Visible effect |
|---|---|---|
| +1 stop | ~30–40% | Modest contrast gain |
| +2 stops | ~70–90% | Clear grain, hard shadows |
| +3 stops | ~2× | Very contrasty, shadows gone |
When it is the right call
When the alternative is no photograph. A pushed frame with hard shadows beats an unexposed one, and the grain reads as intent more often than as error.