Calculating Magnification
Magnification is calculated by multiplying the
magnification of the objective lens with the
magnification of the ocular lens.
The magnification of microscope lenses is engraved
on the lens casing.
What would be the magnification if you used a 10X
eyepiece with a 40X objective lens?
Multiply the eyepiece power by the objective lens
power.
10 x 40 = 400
The magnification is 400X.
What then is the magnification if you have an 8X
eyepiece and a 10X objective?
8 x 10 = 80
The magnification is 80X.
Calculating Field of View
The field of view is the diameter of the circle of
view you can see when looking down a microscope.
The higher the magnification, the smaller the
field of view.
The field of view is calculated by viewing a
microscope slide with a tiny ruler (usually only 1 or 2
mm long) printed onto the surface. By moving the
ruler so that it lies across the diameter, you can
measure the field of view for each magnification on
your monocular microscope.
Once you know the width of your field of view, you
can then make estimates of the size of objects
being viewed under the microscope.
1. If the field of view under low power
(magnification x40) is 1.4 mm, what will be the field
of view under high power (magnification x400)?
1.4 mm at x40
X mm at x400
400 is 10 times bigger than 40.
X will therefore be 10 times smaller than 1.4
X = 1.4/10
X= 0.14mm
2. What will be the field of view under low power (magnification
x150) if the field of view under medium power (magnification
x600) is 0.02 mm?
x600 is 4 times bigger than x150
Field of view will be therefore be 4 times bigger.
4x0.02= 0.08mm or (800 micrometers)