binoculars or binocular telescopes

Binocular telescopes or binoculars (also known as field glasses), are two identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects.

GALI LEAN TELESCOPE Found in 17th century Mounting two telescopes side by side for binocular

vision Convex objective & concave eyepiece lens

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PORRO PRISM BINOCULARS Found by Ignazio porro in 1854 Improved image & higher magnification They are used in keplerian telescopes The disadvantage of keplerian telescope is inverted

images are formed Two prisms are used

Z -SHAPE CONFIGURA

TION

Found in 1870 Purpose is to erect the image Objective lens in line with the eye piece

MAGNIFICATION Ratio of focal length of eyepiece & focal length of

the object gives the linear magnification OBJECTIVE DIAMETER Diameter of the objective lens determines how much

amount light can be gathered to form a image Expressed in millimeters FILED OF VIEW Field of view is determined by the optical design Notated in angular value as how many degrees can

be viewed

General use - hand held binoculars Military use - naval ship binoculars Astronomical – for viewing

planets ,comets and supernova seeking

GENERAL BINOCULAR TELESCOPE

ASTRONOMICAL BINOCULARTELESCOPE

NAVAL SHIP BINOCULAR TELESCOPES

- THANKYOU- PRESENTED BY- MOHAN KUMAR

- A student of shri prakash institute of optometry-DR.AGARWALS EYE

HOSPITAL (Chennai, Tamilnadu)