Abbe condenser

An Abbe condenser is a component of a microscope. It was invented by Ernst Karl Abbe in 1870. The Abbe condenser is mounted below the stage of the microscope, and concentrates and controls the light that passes through the specimen and enters the objective. It has two controls, one which moves the Abbe condenser closer to or further from the stage, and another, the iris type diaphragm, which controls the diameter of the beam of light. The controls can be used to optimize brightness, evenness of illumination, and contrast.

Abbe condensers are more useful at magnifications of above 400X.