substage condenser

 

Although simple, the substage condenser of this Zeiss microscope is a critical component of the optical system.  The substage condenser gathers light from the light source, focuses it such that it illuminates the specimen uniformly across the field of view. The condenser in this Zeiss microscope has two optical positions, one for a low power mode (suitable for the 4X objective) and the second, for the high power ( 10, 40 and 100X) objectives - these are labeled 1 and 2 respectively. It is rotated into either position, using the built in rotation lever (unlabelled arrow). Your microscope may have a different substage condenser system to this. On this instrument, the beam diameter (and thus the depth of focus) is adjusted by using the same lever (arrow) that changes the condenser unit. In other microscopes the substage condenser system can be more accurately focused.  It is critical that the condenser light cone be properly adjusted to optimize the intensity and angle of light entering the objective front lens.