27
11625-101-Rev. L
Instructions for Use
(continued)
Taking Measurements
(continued)
Cross Cylinders
1. The standard cross cylinder cells supplied are
+0.25D. These cells are removable and +0.37D
and +0.50D are available and may be substituted.
2. The power of the cross cylinder is engraved on
the cell.
3. Red dots indicate the minus axis, and white dots
the plus axis.
4. A thumb-operated Roll Knob provides for rapid
“flipping” of cross cylinders.
Refer to Figure IU-8.
Note:
The simplified, synchronized action of the
Cross Cylinder Unit is described in this
manual under “Jackson Cross Cylinder Tests”
in the next section.
Figure IU-8 Cross Cylinder Unit
Roll
Knobs
