At the other end is the objective lens, a concave-convex lens, which curves inward ... We found success with a toilet paper tube, though a paper towel tube should also be effective.

Instead of a concave lens near the eye, Kepler used a convex lens. The result was that ... In 1672, Newton published a seminal paper on light and color, in which he showed that white light is ...

Meniscus lenses — a third broad type also referred to as convex-concave — can be either positive or negative, depending on the curvature of both sides of the lens. A meniscus lens with a steep concave ...

Meniscus lenses are optical lenses that produce a smaller focal point and fewer aberrations than a standard plano-convex lens. Meniscus lenses have one convex and one concave surface with each surface ...