if you can lay your hands on an old book by Peterson's Photographic called Increasing Film Speed (ISBN 71486-54022), you will see detailed description of what it means in terms of the characteristic curve of the negative after push processing. the book is mainly for B&W negative film and is almost 30 years old, but the theory and the measurement techniques for characterizing real speed increase are still the same. a real speed increase is seen when the density range of the characteristic curve of the pushed film is equal to the range of a normally exposed and processed film. the real increase means you can use the same printing paper as with a properly exposed and processed image and get the same contrast. however, you don't need a real increase to get an effective increase because, at least in B&W film, you can use a lower range and a higher contrast paper. provided that all steps of the grayscale are still distinguishable, you will get a good quality print. in color work, you'll have to deal with the contrast digitally.
Herb... ----- Original Message ----- From: "Rob Studdert" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, January 29, 2004 10:21 PM Subject: Re: Developer for Fujicolor Press 800? > You better let Kodak know: > > "KODAK PROFESSIONAL PORTRA 400UC and > PORTRA 800 Films are designed so that you can pushprocess > them to higher exposure indexes. You can pushprocess > PORTRA 400UC Film to an exposure index of 800, > and PORTRA 800 film to exposure indexes of 1600 and > 3200, and produce negatives that yield good-quality prints."
