Push development
Push processing referred to in the analog photography a development technique for underexposed films . The film is deliberately underexposed (for example, in order to still be able to use film material when the brightness is actually too low) and the development is adapted accordingly - normally the development time is extended. For this purpose, for example, a film with ISO 400 is exposed like an ISO-800 film and then pushed with a so-called “+1 development” in order to obtain correctly exposed negatives.
Push development is primarily used for black and white films, but it is also possible for color slide and color negative films.
In push development, the increase in the usable film speed is accompanied by further effects. In most cases, especially with forced application (+2 and more), pushing results in significant quality losses:
- The gradation curve becomes steeper, with high-contrast motifs details are lost in the shadows as well as in the highlights, the representable motif contrast is reduced;
- As a rule, the graininess increases through increased agglomeration of the developed silver particles;
- With slide films, the maximum density is reduced , so that actually black parts of the image appear dark brown or dark blue in the projection ;
- In the case of negative films, there is an increased basic haze , the torture haze .