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Optical instruments
f Likewise, surveyors use binoculars to
That is; m = o survey and observe the landscape and
f
e
other features.
where, f is the focal length of the
o
objective lens and f is the focal length Construction of a simple pair of
e
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of the eyepiece. The quality of images binoculars
formed by binoculars is determined by A simple pair of binoculars can be
the magnification power and the size of constructed using locally available
the objective lens. While the magnifying materials.
power affects the size of the image, the
size of the objective lens affects the clarity Task 6.4
and details of the image. Commercial
binoculars are normally imprinted with Use the locally available materials
information about the objective lens size to design and construct a simple pair
and the magnification power. of binoculars and use them to view
various distant objects. Discuss with
Example 6.4 your class members, factors which
A pair of binoculars, acting as a may affect the performance of your
telescope, produces an angular binoculars.
magnification of 7.5. What is
the eyepiece’s focal length if the Lens camera
binoculars have an objective lens of a The camera is one of the optical
focal length of 75.0 cm? instruments that have been used since
the discovery of lenses. The word camera
Solution is a Latin word that means “a room or
f
m = o enclosure”. Thus, the primary component
f e of a camera is the light-tight enclosure
75.0 cm or box. A camera is made up of different
f = e = 10 cm components contained inside the light
7.5
tight box. Depending on the components,
cameras may take many forms, including
Uses of binoculars film cameras, digital cameras and video
Being able to focus on distant objects, cameras. In this section, we discuss the
binoculars are used in various activities simplest form of a camera, which is
that require the observer to view distant known as a lens camera.
objects in detail. For example, binoculars
are commonly used by tourists to view Structure of a lens camera
animals. Also, soldiers use binoculars to Major components of a lens camera include
view the enemy camp from a far point. a biconvex lens, a film, a diaphragm, a
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