To eliminate shadows, the light needs to be "diffuse"...it can not be "hard light". Diffuse light is coming from multiple directions and it is "scrambled". Hard light is coming from one direction, and is mostly aligned in its direction of travel. The BIGGER the source of light is, the more likely it is to be diffuse. Soooooo, you need something to act as a diffuser...like a large sheet of tracing paper, or an old, very thin, worn out white t-shirt stretched on a frame, as a "diffusing panel" or "diffusing frame". You can also use window screens, which cause the light to come from many,many,many slightly different directions,and prevent the light from coming from one,single, specific point of origin.