Creating believable shadows in Photoshop is something that elevates composite photography. It is something I have found SO hard, over the years. I have tried different methods, all gleaned from YouTube and gathered a couple of go-to strategies. The same strategy doesn’t always work for every image.
Curves and select and mask
Select the area you want to shadow with the Lasso tool. Click select and mask and then feather. The more you feather, the softer the edge of the shadow. Remember, shows and darker and harder the closer they are to the subject.
Use a curves layer to adjust the depth of the shadow. Often a play in the highlights area is enough.
Painting shadows with the brush tool
Select a new layer below your subject, for shadows behind your subject.
Use the brush tool to paint shadows. Keep the brush fairly hard for shadows that meet the subject. I add a new layer for each part of the shadow as it moves away from the subject – dark, mid, light.
Reduce the hardness of the brush as you move through the three layers of shadow. I use a super soft brush for the mid and light shadows.
Reduce the opacity of the brush to as little as 4%. It’s easy to add more depth. Start light.
Sometimes I have 5 or 6 shadow layers for a subject, or part of a subject, adding a bit at a time. Plus it easier to get rid of mistakes!
Top tip for believable brush shadows! – Colour match the brush colour to the shadows on your original subject using the dropper tool!