What is a convex lens?

It is a lens that possesses at least one surface that curves outwards. It causes light to deviate inward, bringing the rays of light to a focus. Its thicker at its center than at its edges, and is used to correct far-sightedness.

A convex lens is a lens that bulges outward on both sides.

I have another comment. It does do all that stuff and who needed them to build a telescope? It's Galileo Galilie. Ohyah!