Swift M3-M Use And Care Manual page 7

FIELD OF VIEW – the area of the object that is seen when the image is
observed. It may range in diameter from several millimeters to less
than 0.1mm, depending on the level of magnification.
FOCAL LENGTH – parallel rays of light after refraction through a lens
will be brought to a focus at the focal point. The distance from the
optical center of the lens to the focal point is the focal length.
NUMERICAL APERTURE (NA) – a measure of an objective's light
gathering capabilities. The concept may be compared to the F-valve in
photographic lenses. Generally speaking, N.A. values of less than 1.00
are "Dry" objectives. Values of 1.00 or greater require oil as a medium.
Please note that condensers are part of the optical system and are also
assigned an N.A. value. That value must be at least as high as that of
the highest objective used.
PARFOCAL – a term applied to objectives and eyepieces when
practically no change in focus is needed when changing
objectives. The objectives on your Swift M3 microscope are
parfocalled at the factory so that only a slight adjustment of the fine
focus knob is needed to maintain focus when switching magnification.
RESOLUTION or RESOLVING POWER – the ability of a lens to define
the details of the specimen at a maximum magnification. This is
governed by the N.A. (Numerical Aperture) of the lens. For example, a
40X objective with a N.A. of 0.65 has a maximum resolving power of
650X, equal to 1000 times the N.A.. This rule of N.A. x 1000 is true of all
achromatic objectives.
WORKING DISTANCE – the distance from the lens of the objective to
the cover slip on the slide, when the specimen is in focus.
Using Your Swift M3
CORDLESS OPERATION – The rechargeable battery should be fully
charged for approximately 8 hours before the initial use. It can be
charged by using the 4.5 volt A/C adapter included with the microscope.
An LED indicator light on the A/C adapter will be red while the battery is
charging and will turn green when the battery is fully charged. The
battery can be used to power the illumination system for approximately
40 hours. If the microscope is used in the same location, the A/C adapter
can remain plugged-in without damage to the battery or recharging
system.
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