As I mentioned in an earlier post, there are now additional sliders that were included with the sharpening tool in Camera Raw 4.1. This first screenshot shows the sliders, with the painted red circle to indicate the icon for the sharpening tool.
Looking at the sliders, the radius slider sets the number of pixels either side of an edge that are going to be effected by the acentuating effect of the sharpen slider. The detail tool increases the fine detail by increasing the contrast effect of whatever setting is set with the sharpen slider. Sliding the detail slider across to its maximum setting will tend to produce a halo around dark/light edges.
The effect of using a high number with the radius slider ‘on top of’ of the detail setting is therefore to create a more blotchy, painterly effect.
The mask tool dampens the effect of the sharpening by working first on the less delineated areas (the cheek and forehead in the following shots) and feathering into the more delineated areas (the eye and hair detail). The masking tool will therefore make less delineated areas smoother and less blotchy, and so moderate the combined effects of the radiusand detailsliders.