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4.1 TROUBLESHOOTING
Problem
When viewing aquatic organisms in a aqueous mount, specimens drift constantly in a sin
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gle direction, making observation and photomicrography difficult.
Solution
Convection currents are being created due to slow evaporation at the edges of the cover
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slip. Place a bead of petroleum jelly or Cytoseal mounting medium around the periphery of
the coverslip to seal it firmly onto the microscope slide. Commercial products are available
that can be added to the water to slow the movement of these minute organisms, making
them easier to photograph.
Problem
When viewing the specimen through a 10x objective, there is a oblong spot of light in the
center of the viewfield.
Solution
The lamp condenser may be incorrectly focused. Re-focus the condenser.
Problem
The viewfield has bright spots and there are problems with achieving sharp focus of the
specimen.
Solution
Small air bubbles may be trapped in the oil between the top of the condenser and the
bottom of the microscope slide. Remove the eyepiece to observe the back focal plane of
the objective, where the bubbles will be visible. To remedy, break the oil contact and remo
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ve any residual bubbles with a cotton swab. Clean excess oil from the condenser front lens
and the microscope slide, then apply a clean drop of oil to the lens. If the problem persists,
thoroughly clean all optical surfaces before re-applying the oil.
Problem
At high magnifications, colloidal particles display incomplete Newton rings and appear to
be unevenly illuminated.
Solution
The condenser is probably off-center. Change to a lower power objective and re-center
the condenser.
