When I started processing files from my first dSLR just two years ago, I was baffled by the concept of sharpening.
Why was it necessary? What was wrong with my lenses that they didn't produce sharp pictures? I never had this problem with film, so what settings do I need to use now? My 5D produces terrific pictures with it's "L" lens right out of the card so why do I even need to do this?
With the help of Amazon.com, by credit card and Scott Kelby's very helpful book "The Photoshop CS2 Book for Digital Photographers" I started gaining a better understanding of this concept. To speed up my workflow, I used Kelby's suggested settings in a job aid that I put together for myself, summarizing the main points in the chart below.
As Kelby points out, these are his suggested settings and you may want to experiment to suit your tastes. I hope you find this chart useful. - Stu