It was the curved shape of the lens that led to its name being borrowed, in the late 17th century, from the Latin name of the lentil plant, lens culinaris. In French, another word for lens is objectif ...

Roland Denning on what exactly is meant when we say a lens is 'standard' and why that meaning may be rather more fluid than many would like to admit. This might seem a simple question, but what is a ...