This could be the start of a long thread. My empiric data suggest that base fog in old film does not improve sensitivity (like flashing or pre-exposure might). In fact all the expired/fogged film I have tested the fog seems to eat away at the toe and make the film slower.
Originally Posted by Michael R 1974
However, fog level is also dependent on degree and type of development. So, one might wonder about a very active developer used to produce super speed but which also gives a high dense fog level. Would the high fog negate any speed benefit of super-active development? Apparently one CAN have very high fog and increased speed as in this example:
Dotted vertical line is the fractional gradient speed point. Delay is the time from mixing the developer; it lost activity quickly after mixing, so time-zero gave both the highest speed and highest fog.
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA
An Evaluation of Film Speeds Obtained with Kodak SD-19A Developer
Last edited by ic-racer; 09-12-2013 at 12:50 AM. Click to view previous post history.