Technical Terms & Concepts
Total Magnification
Total magnification of a microscope is calculated by the magnification of the objective multiplied by the mag-
nification of the eyepieces.
-Ex: (10x Eyepieces) x (4x Objective) = 40x Total Magnification
Field of View
Linear field of view of the eyepiece divided by the magnification of the objective
Numerical Aperture (N.A)
Calculated by n Sin α (max), the Numerical Aperture (N.A) is an important parameter that marks the
features of the objective and condenser’s image quality and resolution. The “n” is a refractive index of the medium
(air
or immersion cedar oil) between the objective lens and the specimen. The “α” is 1/2 of the angle between the
aperture
on the objective and path of light. The larger the N.A, the higher the resolution of the objective (and better
quality of
the image) is.
Object to Primary Image Distance
The distance between the object plane and the primary image plane. The conjugate distance is fixed.
Mechanical Tube Length
The distance between the objective shoulder and the ocular shoulder
Infinity
Infinity is an optic lens system that allows the entire field of view to be in focus at the same time, allowing for
higher quality images to be displayed through the microscope. The focal distance is set to infinity between the objective
and the eyepiece prism, also allowing filters to be inserted into the system more easily due to the parallel path of light,
rather than focusing on a specific point.
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