Most photoshop users know that they can increase the transparency of a layer by lowering the opacity. The fill option does exactly the same, but it does not affect effects that were added using a layer style.

Look at the image below. You can see 3 copies of a circular selection filled with red, with a bevel and drop shadow effect added by using a layer style. The shape on the left has a fill opacity of 100%, the shape in the middle a fill opacity of 50% and the shape on the right a fill opacity of 0%.
Notice that the fill opacity doesn’t affect the effects that were added by using a layer style. The 3 shapes at the bottom that were placed on top of a transparent background clearly show the separate effects, the shadows and highlights of the bevel and drop shadow effect.

One advantage of fill opacity is that it allows you to add multiple layer styles to multiple duplicates of the same object. The next example shows several layer styles that were added to the same objects, duplicates which layers all have a fill opacity of 0%. The result is something what never could have been achieved with a single layer style.

Tomorrow I’ll show another use of fill opacity.

Fill Opacity

Multiple Layer Styles