Always put some type of bag over your magnifier when not in use. You can easily make or buy a cloth bag with a draw string or elastic band. Because the light shines on all sides of your piece as seen through the magnifier, no shadows are cast. Makers of this style of lamp claim this as an advantage. Your stitches look flat but are thoroughly illuminated.
Incident light occurs when the light source is to one side of the magnifier.
Hold the flashlight directly over the piece and you can see shadowfree illumination. The type of light you prefer is a personal, and important, choice 2. Be aware that different types of bulbs generate different amounts of heat. Fluorescent bulbs are the coolest. Incandescent are hot.