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(7) Field and Aperture Diaphragms
• For brightfield photomicrography
Stop down the field diaphragm until its image is slightly larger than the diagonal
dimensions of the film format to restrict excessive light which may cause a flare.
Stopping down or opening the aperture diaphragm changes depth of focus, contrast
and resolution. Adjust this diaphragm in accordance with the sample.
Generally, it is appropriate to stop down the field diaphragm to the range of 70 to 80%
of the numerical aperture of the objective in the optical path.
• For darkfield photomicrography
Fully open the aperture diaphragm.
(8) Voltage
Since the color temperatures of a light source vary with lamp voltages, the results of
Film
I
Color film
8/Wfilm
color photomicrography depend considerably on how to set appropriate voltages.
The table below shows common combination of lamp voltages and the filters.
(9) Exposure Time
The exposure time should be set between 1/4 and 1/15 of a second.
*
How to set exposure time.
Exposure time is displayed within the range of
0.01 to 999.99 seconds (1/100 of a second to
approximately 16 minutes) according to the
measured brightness of the sample. The display
of the exposure time changes by the reflectance
of a sample, ISO value setting and the aperture
diaphragm setting. If the exposure time to be
set is outside the above range, "J.." (over-
"I"
exposure) or
CHECK display is indicated by the lighted
LED, and the shutter is locked.
• For color photomicrography
Adjust the brightness with ND filters to change the exposure time. (Do not raise or
lower the lamp voltage to adjust the exposure time.)
• For B/W photomicrography
Change the lamp voltage or use ND filters to adjust the exposure time.
Daylight-type film
(under-exposure) on the
Voltage
9V
NCB11
6V or above
Under-exposure
Filter
(GIF)
Over-exposure
CHECK
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