An
eyepiece, or
ocular lens, is a type of lens that is attached to a variety of optical devices such as
telescopes and
microscopes. It is so named because it is usually the lens that is closest to the eye when someone looks through the device. The
objective lens or mirror collects light and brings it to focus creating an image. The eyepiece is placed near the
focal point of the objective to magnify this image. The amount of magnification depends on the
focal length of the eyepiece.