I tried adjustment brushes for the two shots shown below in Lightroom 3. Shot of Herkko (the dog) was quite badly overexposed and in first hand I though the shot was going into the trash can. But then I decided to lower the exposure over two stops and the grass area and Herkko’s back was quite nicely recovered. Herkko’s head and chest were, however, very dark after tweakin the exposure. Then I decided to use Adjustment brushes and I lightened up his head and chest area selectively. I used quite mild tweaks with brightness and exposure sliders. And I immediately noticed that this shot is going to be useable after all! Wow. I also applied some clarity and sharpness for the head area using third adjustmen brush. I really like how you can see all the time the effect overlay for the selected adjustment brush in Lightroom 3. It is so much easier now to do the area selection.
I used adjustment brushes also for the dandelion shot below. I added some brightness and clarity for the yellow area and now the flower pops nicely out I think. In combination with some mild vignetting (which is much more nicer in LR3 than in previous versions) I am happy with the result.