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convenient, or allows the microscope to be shared by simply rotating the
head.
IRIS DIAPHRAGM (M2251C, M2251CL) - a round multi-leaf device
mounted below the condenser which is controlled by a lever. It is similar
to a camera shutter and controls the amount of light entering the
condenser, allowing the user to control contrast.
NOSEPIECE – a revolving turret that holds the objective lenses,
permitting changes in magnification by rotating different powered
objective lenses into the optical path.
OBJECTIVES – the optical systems which magnify the primary image of
the instrument. Typical magnifications are 4X, 10X, and 40X.
STAGE – the platform on which the specimen slide is placed. The
standard version comes equipped with locked-on stage clips, and is
pre-drilled to accept an optional mechanical stage.
TERMINOLOGY
“COATED” LENS – in attempting to transmit light through glass, much of
the light is lost through reflection. Coating a lens increases the light
transmission by reducing or eliminating reflection, thus allowing more
light to pass through.
EYE POINT or EYE RELIEF – the distance from the eye lens of the
eyepiece to your eye where a full field of view is seen.
FIELD OF VIEW – the actual circular area seen through the eyepiece.
PARFOCAL – a term applied to objectives when very little fine focusing is
needed to bring the specimen into focus when changing objectives.
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 N.A. 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.
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