Leitz microscope condenser

Multi-leaf adjustable condenser iris.
The condenser has an adjustable iris, controlled by knob A, and a removable filter carrier (B).
The condenser press-fits into this brass fitting.
Installed condenser swung out of the light path.
The axial position of the condenser is fixed using this locating pin (arrow).

Condenser is focused by turning knob "A".