How to Feather a Selection Using the Keyboard in Photoshop CS6
In Photoshop CS6, most users initially learn how to feather (blur the edges of) a selection when using the Lasso and the Marquee tools by entering a value in the Feather box on the Options bar. This method of feathering requires that you set your feather radius before you create your selection.
Unfortunately, using this method, a problem arises if you want to modify the initial selection. When you select with a feather, the marquee outline of the selection adjusts to take into account the amount of the feather. Therefore, the resulting marquee outline doesn’t resemble your precise mouse movement. As a result, modifying, adding, or subtracting from your original selection is pretty tough.
A much better way to feather a selection in Adobe Photoshop CS6 is to make your initial selection without a feather. Clean up your selection as you need to, and then apply your feather by choosing Select→Modify→Feather. In the dialog box, enter a Feather Radius value and click OK. After a learning period of trial and error, your work will improve by using this method.