What is the best lightbulb to cast a shadow?

The sharpest shadow will be cast by the light source which is closest to an ideal point source. In my experience, the best light source for casting a shadow is a single-LED bulb, like this: Edit to add for Colby Parsons: Re: ideally I want options that are directional like a spotlight. read more

Milan 2013: designer Dennis Parren has developed a light bulb that casts coloured shadows. The CMYK bulb by Dennis Parren combines a white main light source with coloured LEDs in red, green and blue to cast shadows in cyan, magenta and yellow. read more

Clear bulbs create the sharpest light that sparkles and generates more shadowing. Clear bulbs may create undesirable spotting and shadows in diffusing fixtures made with paper. We recommend using clear bulbs in woven fixtures (i.e., Roost Pendant, Thicket Sconce) to enhance the sparkle and shadow patterns. read more