The scanning objective on a light microscope is located where on the instrument?

• A. At the upper end of the body tube
• B. At the lower end of the body tube
• C. In the ocular assembly
• D. On the stage

Answer: (B)

The scanning objective is the lens mounted in the revolving nosepiece and sits at the lower end of the microscope’s body tube, just above the stage where the slide rests. This position places the lens directly in the light path first as it moves from the specimen to the eyepiece, which is why the scanning objective—typically the lowest magnification (and widest field of view)—is located near the bottom of the optical column. The oculars are up at the top of the tube, and the stage is the platform holding the slide, so those areas are not where the objective lenses live.