Originally Posted by jdef
Obviously to extend the density range (contrast) does require one of or quite probably two different things. The first being that of increased developer activity and second longer development time. Not all films are equal in their ability to extend density range.
It seems that C6H6O3 and I have differing views on what we are experiencing with our camera negatives and Azo. My tests using a transmission densitometer in conjunction with a reflection densitometer indicate a certain density range negative will work with Azo grades two and also a certain camera negative density range will be accomodated by grade three. There is nothing inherently different in this regard then any other photosensitive paper and film combination.
What C6H6O3 is indicating is that his experience is that a higher overall density in the camera negative is producing prints more meaningful to him in his practice. By this I understand him to say that overexposing and overdeveloping the negative is providing results that he wants.
My experience is somewhat different in this regard then Jim's experience. My experience indicates that by overexposing film I hinder the ability to build the density range (contrast) that the camera negative can produce. My experience indicates that this keeps me from experiencing all of Azo's long exposure scale potential. The results that I am obtaining are meaningful and satisfactory to me.
As in all things this is another of those times when things are not clearly defined. What overexposing the film will accomplish is moving the shadow densities up off the toe of the film's characteristic curve. This will provide better shadow value separation. This will, as I indicated earlier, cause a decrease in the overall contrast that the film is capable of producing. Proper exposure of the film will have somewhat lower shadow value tonal separation but will accomplish more in upper value separation. This is due to the fact that the film is recording the information on different portions of the film's characteristic curve. The film if overexposed will tend to place the high values on the shoulder of the film's characteristic curve. This will tend to hinder high value tonal separation as the expense of greater shadow tonal separation.
Sometimes we get so caught up in discussing things that we tend to discuss terminology rather then practice. I hope that my understanding of practice has been indicated by this.