通过照相机取景的设备请参见取景器。

目镜，又称接目镜，通常是一个透镜组，可以连接在各种不同光学设备，像是望远镜和显微镜，的后端。所以如此命名，是因为当设备被使用时，它常是最接近用户眼睛的透镜。物镜的透镜和面镜收集光线并引导至焦点生成影像；目镜被安置在焦点，主要的功能在放大影像，放大的倍率则与目镜的焦距有关。

目镜通常会包含几个组装在一起的「透镜组件」，装在一个筒状物的后端。这个筒状物则会塑造成适合仪器的特别开口，影像可以经由移动目镜和物镜焦点的位置而聚焦成像。多数仪器都会有一个聚焦的设备，允许目镜在轴上移动，而不需要直接去操作目镜。

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.