The cylinder iris diaphragm comes into play when the condenser is swung out of position. To do this the diaphragm carrier is turned to the side as shown in the diagram, a small knob is pressed, which liberates the condenser, and the latter is swung out to the side.
The regulation of the cylinder iris diaphragm is accomplished by means of a lever. Before the condenser is swung back into position the cylinder iris should be opened to its fullest extent. The lower iris diaphragm is for use in connection with the condenser only. It is regulated by means of a small knob. A horizontal rack and pinion arrangement permits oblique illumination, and a vertical rack and pinion permits adjustment of the whole sub-stage. By these means a most perfect control of the illumination of the object is assured. Ground or colored glass discs may be inserted above the iris diaphragm if modification of the light is desired.
$30.—
This illuminating apparatus may also be fitted to Stands Ia and Ib.
Abbe's Illuminating Apparatus for Stand A and I.
Swing-out Condenser.
Cylinder Iris Diaphragm.
b. Illuminating Apparatus of Stands Ia and Ib (p. [30], [32], [34]).
The following are the parts of this apparatus: