24
11625-101-Rev. L
Instructions for Use
(continued)
Taking Measurements
(continued)
Cylinder Power and Axis
1. In the Cylinder Lens Dials, which are
controlled by turning the Cylinder
Power Knobs, the powers range from
0.00 to -6.00D for instruments contain-
ing minus cylinders, and from 0.00 to
+6.00D for instruments containing plus
cylinders.
2. Cylinder power can be changed in
steps of 0.25D throughout the full
range by means of the Cylinder Power
Knob.
3. To increase power, knobs are turned
clockwise. Refer to Figure TM-5.
4. A pair of 0.12D cylinders in accessory
cells permits refinement to 1/8th D
steps.
5. A pair of 2.00D cylinders in accessory
cells extends cylinder power range to
8.00D.
6. Large 360° protractors around the Cyl-
inder Axis Knobs mark the position of
the axis from 0° to 180° in steps of 5°.
7. The Rx axis reading is taken from the
scale at the Cylinder Axis Knob.
8. The axis scale around the aperture is
provided for reference during retinos-
copy.
9. The Cylinder Axis Knob (concentric
with power knob) can be continuously
turned clockwise or counterclockwise
to set the axis of the cylinder in any
meridian from 0° to 180°.
Refer to Figure TM-6.
Figure TM-5 Turning Cylinder Power Knob
Figure TM-6 Turning Cylinder Axis Knob
