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TELESCOPE

Andre Anthony

Hansel Bunardi

Felicia Limenkoh

Fani Agusta Chandra

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HISTORY

1. First refracting telescope (1608)Hans Lippershey, Zacharias Janssen

and Jacob Metius

2. Galilean telescope (1609)

3. Keplerian telescope (1611)

4. And many more...

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HISTORY

5. Gregorian telescope(1663; model of reflecting telescope)

6. First reflecting telescope Newtonian telescope

(1668)

7. Cassegrain telescope (1672)

8. And many more...

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A tool

Function : to observe

objects closely and clearlywhen they are very far away

Objects : celestial objects& terrestrial objects

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TELESCOPE

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_

)(_

_

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(OBL) Lens which is placed near theobjects

MUST CONVEX LENS. Why?

Form real image at its focal point.

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OCULAR LENS (OCL)

Lens which is placed near the

eye

MAY BE CONVEX OR

CONCAVE lens

Enlarge the real image

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SO,Length of telescope

(distance between ObL n

OcL)

=Fob + Foc

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GALILEAN TELESCOPE

By Galileo Galilei

ObL : convex lens

OcL : concave lens

(+) : Upright (-) : Blurry, distorted

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KEPLERIAN TELESCOPE

By Johannes Kepler

ObL and OcL : convex lens

(+) : Rays are converging (more

focus), Wider field of view

(-) : inverted

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MAGNIFICATIONOf Refracting Telescope

=Fob____

Foc

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Simple design

Excellent for moon and planets

(planetary)

High contrast

Not good for Nebula and Galaxy

viewing (deep sky)

Heavier and longer than reflector

telescope

Chromatic aberration happens

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Chromatic Aberration

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TELESCOPE

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Gregorian telescop

l

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GREGORIAN TELESCOPE

By James Gregory

Upright image

For terrestrial observation

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NEWTONIAN TELESCOPE By Isaac Newton

Upside-down image

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CASSEGRAIN TELESCOPE

By Laurent Cassegrain

Upside-down image

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Low cost

Excellent for deep sky viewing

Good for planetary viewing

Bright image Light loss due to secondary

mirror

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FORMULA

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hh

f

fss

o

i

o

i

oc

ob

oi

M

f

111

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PROBLEM1. The focal length of two convex lenses is

10cm and 20cm (fob,foc). Both lenses are

seperated by 50cm. An object is in frontof the first lens that has an image in the

middle of both which is 31cm away from

the first lens.a. Find the object length of the first lens

b. Find the final magnification

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PROBLEM2. Two convex lens with the focal length 25cm

and 5cm are separated by 70cm. A candle

is placed 50 cm from the first lens. Theposition of the final image is...

3. What are the magnification and the

distance between both lens if the focallength of a galilean telescope are 20cm

and 4cm (obl,ocl) and the image form is at

infinity?

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Quiz Baby!

1. A space telescope (keplerian telescope) has focal length of objective

and ocular lens which are 50cm and 2cm consecutively. The

telescope will form an image at infinity. Determine :

a. The magnification of the telescope

b. The distance between both lenses

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Quiz Baby!

3.The focal length of the objective and ocular lens of a Keplerian

telescope are 20cm and 10cm consecutively. The distance

between both lenses is 40cm.

Find the image position of the convex lens of an object that is

placed 100cm in front of objective lens.

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