Sizing a brush in sculpt mode

When I hold down F to resize my brush I get two red rings. One of them moves when I’m holding down F and the other seems to move when I’m not. Which one is doing what? I assume one adjusts the size of the brush and the other the sensitivity of the brush? Did I explain that ok? Do you know what I mean?

Btw, I’ve only been doing Blender for a day now, and almost all of that has been in Sculpt mode doing the sculpt a human head tutorial, so I don’t know most of the tools in the other modes yet.

One ring is the current brush size, the other ring will be the new brush size. You can use Shift+F to adjust the brush strength
Sculpt wiki entry http://wiki.blender.org/index.php/Doc:2.5/Manual/Modeling/Meshes/Sculpting

I see what my problem was. I was holding F while resizing the brush, then getting confused as to why it appeared to continue resizing after I let go of F. I only need to press F and release in order to resize. Because of this it was giving me the mistaken impression that one way was moving one ring and the other moving the other ring.

it would be nice if they changed this to how Sculptris Traditional navigation and Mesh Mixer does it…
Shift + Mouse wheel up/down = Brush size…
Ctrl + Mouse Wheel up/down = Brush Strength

Also make it just like Sculptris how the circle gets lighter and darker with the brush strength…