In the latest View Camera magazine there are two good articles on scanning large format film. The first, by Charles Cramer, strongly advocates not applying any sharpening (unsharp mask) tothe scan. In his work flow, he applies unsharp mask as a final step in photoshop. He says that the degree of sharpening is dependent on the target for your output. He says bigger files need more sharpening to achieve the same effect.
The second article, by Michael Mutmansky, advocates sharpening as part of the scan. he suggests that, if you don't know what your final output will be, apply just enough sharpening to just offset the softening inherent in the translation of analogue to digital. His overall goal is to get a scan that is pretty close to the image you want and then use Photoshop to just tweek the image.
I have been experimenting with both approaches and would be interested in comparing notes with others who are trying to (or who have) figured this out.
I'm using a Imacon 646, but previously used an Epson 4870. The Flexcolor software that comes with the Imacon has an additional unsharp mask control that Photoshop doesn't. With Flexcolor I can prevent any sharpening in the dark tones below a specify level. This eliminates the most obvious noise problems that result from sharpening. This seems to be one of the advantages of sharpening as part of scanning. Another is that my initial image in Photoshop is a little closer to my final goal and helps guide the rest of my adjustments. On the other hand, applying unsharp mask after setting all tonal adjustments makes sense. However, that process seems to take a lot more time because of the recommendation to save a master file, then flatten the image, then apply the unsharp mask. After doing so, I have often felt that further tonal adjustment were in order. That mean re-loading the master file and repeating the process.
Which approach are you all finding is most successful? How does resolution and print size affect your decision on how much sharpening to do (assuming you're working with the same subject matter)?