Nikon Eclipse Ni-E Instruction Manual page 116

Manually adjusting the condenser aperture diaphragm
When using a manually-operated condenser, use the condenser
aperture diaphragm lever for adjustment. Moving the lever in the
clockwise direction will open the diaphragm.
The manually-operated condenser has a scale that indicates the
numerical aperture. Align the index on the aperture diaphragm
lever with the scale line that corresponds to 70 to 80% of the
numerical aperture of the objective to use.
The numerical aperture is indicated on the side of the objective.
For a numerical aperture of 0.75, the index should be aligned
with the scale on the condenser at 0.525 to 0.6.
Or, pull out the eyepiece and look into the tube to view the pupil
of the objective (bright area when the aperture diaphragm is fully
opened). Adjust the aperture diaphragm lever so that the size of
the aperture diaphragm becomes 70 to 80% of the pupil.
Adjusting the aperture diaphragm using the
centering telescope
(1) Remove one eyepiece and attach the centering
telescope in place.
(2) Using the DIA aperture diaphragm button or the
aperture diaphragm lever, stop down to the minimum
aperture diameter. While holding down the flange of
the centering telescope, turn the eyepiece of the
centering telescope and focus on the aperture
diaphragm.
(3) Using the DIA aperture diaphragm button or the
aperture diaphragm lever, adjust the aperture
diaphragm. Normally, the aperture diaphragm should
be adjusted to around 70 to 80% of the size of the
field of view.
(4) Remove the centering telescope and reattach the
eyepiece.
Chapter 3
Individual Operations
102
Aperture
diaphragm lever
Adjusting the aperture diaphragm
Plan 40X
40x / 0.75
/ -WD
Indication for 40x magnification
/ numerical aperture 0.75
Proper numerical aperture: 0.75 x 0.7 to 0.8＝0.525 to 0.6
Eyepiece
Using the centering telescope
Nikon JAPAN
Plan 40x
40x / 0.75
/ -WD
Centering telescope
Flange