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. 聚光鏡裝配有瞳孔膜，那是一個(gè)有貢桿控制的快門(mén)，用來(lái)調節進(jìn)入鏡頭系統的光量。
The focal length of the conelensing lens should be such that the image of the source just fills the projecting lens. 聚光透鏡的焦距應使光源的像正好照滿(mǎn)放映透鏡。
It's an easy matter to observe chromatic aberrations, with a thick, simple converging lens. 用一厚的簡(jiǎn)單會(huì )聚透鏡很容易觀(guān)察色差。
