SIlverfast has an option they call AACO which stands for Auto Adaptive Contrast Optimization.
Usually, when I am scanning black and white film, anything which is described as Auto makes me look for the option to disable it bu this may be an exception.
According to the user guide, SilverFast AACO is a tool used to lighten up shadow areas, which are too dark, without changing mid-tones and highlights. Thus, image details get visible in dark, low-contrast image areas that otherwise would remain hidden.
I wanted to put this to the test for myself so I dug out my trusty test negative which I exposed on the Pentax 35mm Spotmatic and developed in Diafine.
My first test was to scan the negative in VueScan which I could then use as a benchmark for when I used the AACO tool in SilverFast.
Areas of concern
The areas of concern are the shadow areas under the front of the lens and to the right of the garlic. Although the transition to nearly black is pretty good in parts, looking and measuring the density on the negative told me that there was more detail present there than what the scan was showing.
I opened SilverFast 8 AI and then from the main interface I chose the AACO tool from the tool bar
Under the Expert Mode you have the ability to change the overall strength of the effect as well as the shadow width which means how far into the shadow areas do you want to go.
Applying the AACO tool really opened up the shadow areas to give a much more pleasing look and greater tonal separation in the areas which was of concern in the VueScan scan.