APPLICATIONS DEVELOPING BLACK & WHITE FILMS
Push processing is a technique that compensates for underexposed film by over- developing it at the processing stage. Push processing is commonly used as a deliberate attempt to obtain usable images when working in poor lighting conditions, but the method is also necessary on occasions when a film has been underexposed accidentally.
It is normal to use an active, “speed-enhancing” developer for push processing, such as ILFORD Microphen or ILFORD Ilfotec DD-X, and also to develop for a longer time or at a higher temperature than normal; see the fact sheets for individual ILFORD films or the ILFORD Film Processing Chart for development time guidelines. The resultant negatives have greater grain and contrast, lose some detail in shadows, and may be difficult to print well. On the other hand, there are circumstances when the effect of gritty, contrasty images is desired. The increased contrast may also be useful when shooting in dull, overcast conditions; an increase of development time by about 20% will boost contrast a little.
Certain films, such as ILFORD HP5 PLUS and DELTA 3200 professional, are designed to respond well to push processing. The push processing application sheet provides further details; some experimentation using test exposures is recommended before any critical work.
Push processing is only of use if the complete roll of film has been underexposed in this way. It is only necessary to change the developing times, not the fix or wash times. Push processing is not needed with ILFORD XP2 SUPER film which has great exposure latitude and can be exposed over a wide EI range with normal C41 chromogenic processing.