There are two different sliders (Detail and Masking) used to create and control the masks used suppress sharpening in the lower contrast areas of an image. As a rule of thumb, use the Detail slider to suppress sharpening in landscape images, and use the Masking slider to suppress sharpening in portraits. To view a Black and White preview of the masks, Option (Mac) / Alt (Win) -drag the Detail and/or Masking slider.
It is best to view an image at 100% to see the effects of sharpening (as well as noise reduction) accurately. If you prefer to remain at a different zoom view in the image preview area, click the disclosure triangle to the right to the word Sharpening in the Detail panel. Then, click the square icon to pick it up and click in the image preview area over the area that you would like displayed at 100% in the Details panel. This will allow you to see a small area at 100% in the panel while viewing a different view in the preview area.
In this episode of The Complete Picture (New Camera Raw Features in Photoshop CS5), Julieanne Kost goes over all the new refinements and enhancements you’ll find in the latest version of Adobe Camera RAW including Noise Reduction and Image Sharpening
