#79 Darkening the Sky
One of the most common uses for the Graduated Filter tool is to correct an image when the subject is correctly exposed but sky in the background is overexposed. (This is how traditional film photographers use a graduated filter on a camera lens and where the idea for the building a digital version of the filter originated.)
To darken the sky, select the Graduated Filter tool. Click on it in the tool strip, choose View > Graduated Filter, or press the M key. Next, modify the controls to darken and increase the contrast of the sky (Figure 79a). While the actual settings will depend on the brightness of the sky, try these example amounts as a starting point. Most important, lower the Exposure significantly. Finally, slightly lower the Brightness. Increase the Contrast, Clarity, and Sharpness. Keep in mind that if these control settings don’t work with your image you can always change them after you have applied the tool.
Now that the controls are set, click on the area of the photo where you would like the effect to occur. With the examples below, I have clicked above the horizon and dragged down (Figure 79b). Next, continue to press the mouse button and drag to increase the transition or fade of the effect. Click and drag farther away from the initially clicked area to increase the transition. Click and drag less distance to shorten the transition. Or click, drag, and rotate to change the gradient direction, as was done in the example on the left.