What is a Lens A lens is a curved and polished piece of glass or any other transparent material. The most common place where you will find lenses is in spectacles. You will also find lenses in magnifying glasses, binoculars, and in cameras.Fig. Lenses used in spectacles Common lenses are of two types: convex and concave. A convex lens is thicker in the middle than at … [Read more...] about What is a Lens