The condenser is equipped with an iris diaphragm, a shutter controlled by a lever which is used to regulate the amount of light entering the lens system. 聚光镜装配有瞳孔膜，那是一个有贡杆控制的快门，用来调节进入镜头系统的光量。
The focal length of the conelensing lens should be such that the image of the source just fills the projecting lens. 聚光透镜的焦距应使光源的像正好照满放映透镜。
It's an easy matter to observe chromatic aberrations, with a thick, simple converging lens. 用一厚的简单会聚透镜很容易观察色差。
