The scioptic ball was used to project an external image onto one side of a camera obscura, or to harness the Sun as an effective light source. This example, made of mahogany, consists of a hollow sphere rotating freely inside a square frame with four brass screws in the corners. Two lenses are fitted in diametrically opposite compartments in the sphere. Outside each compartment is a threaded screw to be fixed to a microscope or a projection telescope. When the microscope or telescope is aimed at the Sun, its image can be projected on a screen. The instrument was substantially improved by adding an adjustable mirror to reflect the Sun's rays. This allowed the projection of microscope images.

The optics collection of Benjamin Martin (c. 1760) has a scioptic ball attached with a cylindrical screw to a regular microscope so as to form a solar microscope (Science Museum, London, inv. 1918-64).