What does iris diaphragm do?

• A. Focuses the light onto the slide
• B. Magnifies the image
• C. Controls the amount of light entering the condenser and helps to control glare
• D. Adjusts the stage position

Answer: (C)

The iris diaphragm controls the amount of light entering the condenser, shaping the cone of illumination that reaches the specimen. By adjusting its blades, you regulate how much light passes through, which in turn affects glare, contrast, and overall image quality. When the diaphragm is narrowed, less light gets through, increasing contrast and reducing glare, though brightness drops and fine details at high magnification can become harder to see. When opened, more light comes through, brightening the image but potentially washing out details and increasing glare. This component works with the condenser to optimize illumination for different objectives and specimens. It does not focus light onto the slide, magnify the image, or adjust the stage position.