Uxcell 200mm 300mm Focal Length Double Convex and Concave Lens Set, Glass Optically Lens Classroom, Clear

Double concave lenses are used to disperse light. The double convex lens is a type of lens that is thicker at the center than at the edges and is used to gather light. They can make telescopes, suitable for a variety of applications, including scientific experiments, photography, and optical instruments.

Advantage
Made of quality glass that is durable, scratch resistant, and provides excellent optical performance. Round edges have been polished, it is not easy to hurt your hand when you assemble it.
Designed with a double concave shape that let the light diffuse and produces virtual images. The double convex shape of the lens provides a wider field of view, resulting in clearer and sharper images.
The lens is accurately measured and has consistent curvature, ensuring consistent performance and results.

Instruction
Concave Lens: Place the concave side of the lens facing the object from which you want to disperse the light. Adjust the distance between the object and the lens until the desired level of dispersal is achieved.
Convex Lens: Once you have determined the focal length, position the lens in front of the light source. The side of the lens that is curved outward should face the object you want to focus the light on. Move the lens back and forth until the image of the object is in focus on the screen or surface.

NOTE: Double concave lenses are often used in combination with other lenses to create specific optical effects. Remember to handle the lens with care to avoid scratches or damage to the surface.