When you work with masks or brush in editing, to do the job well, you need to make changes to brush size, opacity, hardness, and fill while you work.

If you want to make changes while you brush without leaving your place to adjust settings on the Options Bar, you can instead use these helpful keyboard shortcuts.

• To reduce the size of the brush, press the left bracket key "["
• To increase the size of the brush, press the right bracket key "]"
• To harden the brush, use Shift + [
• To soften the brush, use Shift + ]

When a brush is active, pressing a number key results in Opacity setting of 10x the number (e.g., 1 = 10% opacity, 5 = 50% opacity, 0 = 100% opacity). If you hold down the shift key and press a number key, you affect flow instead of opacity. Flow controls how fast a brish builds up to the current opacity level.

If you press two numbers in quick succession, you can get even finer contol. For example, pressing 1 followed by 5 results in 15% . For opacity levels less than 10%, just press the 0 key followed by a number. 0 followed by 5 becomes 5%.

I use this technique all the time when brushing in dodge and burn effects with an Overlay layer. It's also great when using Paint With Light techniques.

Get Your Dodging & Burning Under Control (.PDF)
Get Your Dodging & Burning Under Control (Quicktime)
Low Key Lighting Effect

I hope you find this tip helpful in your digital photography.