Photomicrographic - Nikon Epiphot 300 Manual

4. Photomicrographic

Symptoms
• Inappropriate
• Focus shifts especially
Image not
sharp.
• Influence of
• Cover glass attached
• Grease, dust, dirt or
Image blurs.
• Adjustment of
Photo taken
uneven.
• Use of field diaphragm
Contrast not
sufficient.
67
Causes
focusing.
when using high
magnification
objective for long
exposure time.
instantaneus vibration.
to the sample.
finger-prints on optical
system.
illumination system
incomplete.
Photomicrography is
more affected by
incomplete
illumination system
than microscopic
observation is.
• Aperture diaphragm
opened too wide.
• Use of filters
inappropriate.
inappropriate.
• Specimen with little or
no contrast.
Actions
• Look into the eyepiece with the photomask and rotate
diopter correction ring to focus on double crosshairs.
Turn your face slightly to right and left to see relative
positions of crosshairs and specimen image from
different angles. Rotate fine focus knob until the
relative position becomes stable (utilization of
parallax).
• Use focusing magnifier for low magnification
objective. (P. 59)
• Install microscope on vibration-resistant mount or
robustly-built desk to eliminate external vibration.
• Operate microscope in a place free from vibration,
such as caused by other persons.
• Use ND and other similar filters to extend exposure
time (between 1/4 and 1/15 second for color film).
• Reduce lamp voltage to extend exposure time for
monochrome film. Note that film's spectral
characteristics slightly vary with reduced color
temperatures.
• Do not use cover glass.
• Clean top of objective, uppermost part of eyepiece,
specimen, projection lens or the like. Pay
uninterrupted attention to cleaning and custody of
optical system. When not in use, put cover on
microscope.
•
Readjust it correctly. (P. 18~22)
•
Immediately replace old, blackend lamp. (P. 5, 6)
• Stop down diaphragm to 70 ~ 80% of objective's
numerical aperture to obtain good photomicrographic
results. (P. 35)
• Use GIF filter to enhance contrast on monochrome
film.
• Stop down diaphragm slightly larger than diagonal
dimensions of film format. (P. 60)
• Change over to darkfield or differential interference
contrast microscopy to optically give contrast to
specimen.
(P. 27~30)
• Use fine particle, high contrast B&W film (such as Mini
Copy Film) for the specimen with little contrast.
• Use high latitude, fine particle film (such as Neopan F)
for normal specimens.