The lens on a camera is what focuses light onto the focal plane to create an image. It is a cylindrical tube that holds a series of concave and convex lens elements. Light enters the lens through a hole or aperture and is bent to a focal point by the series of lens elements. Depending on the quality it will be made of plastic or glass.
Here's a short guide to shooting several photographs to make an ultra sharp close focus shot. We will explain how to shoot, and then what software will combine the shots to give you ultra sharp results.