I am in the process of scanning my old negatives using a Coolscan 5000 (the Great Project). I use GEM in Nikon Scan to tame the grain in the first pass. I have been doing some minor tidying up on the scans using Photoshop - to which I am also new. In that process I have been using unsharp mask at the end before sending the happy snaps to iPhoto as JPEGs. At first I was using settings of Amount:125%, Radius: 2, with threshold varied to limit the extent to which grain in skies got emphasised. (I am scanning consumer 400ASA film - Kodak Gold or similar - that seems to be quite grainy.) While this seemed to work OK I was never really happy with the way it interacted with skies and the remaining grain. (Although this was an opportunity to learn about masks to mask off the sky when sharpening.) In my experimentation last night I stumbled upon settings of Amount: 50%, Radius: 4 with threshold 0, or maybe 1 and it seemed to be working like magic. Grain wasn't getting emphasised but features were getting sharpened nicely. The results seemed to be much less noisy but the sharpening was just as good. Can someone help me understand what is going on and why the large radius low amount settings might be working so much better for me? Is there a downside to these sort of settings that I have overlooked but will be terribly annoying as soon as someone points it out to me?