The main light casts the shadows.
The fill “light” brightens the shadows.
The fill in a photo studio may be another light but in my home window studio I am using a piece of white computer paper to reflect the main light – which is the light from the window – back onto the garlic to brighten the shadows and even out the light.But
Adding fill evens out the light. It reduces contrast. You can’t simply correct for this is post. when you do, you will lose detail in the brighter areas to get a good exposure on the areas in shadow. Look at the garlic in the back. Without fill, the detail is lost.
Photograph a small object by a window with and without fill. Post your two original files. Then adjust the two files so that the image looks as good as possible with a good tonal range. Label all four files and put them in a post under the category Week 11 – Food Photography – Fill.