I just discovered this technique while reading a French magazine. And to my great amazement, it really works!
They published an article on negative scanners which made me smile a lot for a good reason. They compared a 120 negative scanned with a Hasselblad Flextight X1 and an Epson V700. And by comparing images, they came to the conclusion that the results between both are so close that no real difference can be seen between both images.
But back to the technique...
Most flatbed scanners suffer in resolution because of the glass which changes the light path slightly. When scanning a B&W negative, you can get much greater resolution by scanning as 48 bit RGB than grayscale. When scanning grayscale, the driver mixes all colors equally which results in a slightly fuzzy image. Here is a simpler step by step of what they suggest.
1 - Scan as RGB 48 bit (16 bit per color) slide material with medium sharpening,
no grain reduction and
no DigitalICE.
2 - Invert the image to a positive (ctrl-i in photoshop)
3 - Open the channels layer box and inspect each colored layer individually. You will notice that some will be a lot sharper than others!
4 - Open the Adjustments/Channel mixer, check the monochrome box and set to 100% the layers you want to keep. Put the undesired layers to 0%
5 - Convert the image to 16 bit grayscale.
6 - Put the color profile to Gamma 2.2
That simple. Here are the screen captures... tell me what you think
[Sorry, image deleted during forum software upgrade. Please re-upload if so inclined.]