2. Definition
Telescopes â are instruments used to observe
remote, distant objects. It collects and focuses light coming
from the observed object, resulting to a clearer, magnified
image of it.
* We need magnification for our eyes donât have enough space to see distant things. Pixel
example.
3. A Bit of History
⢠Coming from the word âteleâ â far and âskopeinâ â As of now,
far seeing. from the simple
⢠Since its invention in 1608 by Hans Lippershy, it lens ancestor, it has
has been widely used in Astrophysics. Galileo was evolved into
considered the father of telescopes. gamma ray,
⢠Galileo first used a telescope for astronomical infrared telescopes,
purposes. basically the types
⢠Kepler improved the design further using two of electromagnetic
convex lenses. waves available.
4. ⢠Properties
â Aperture â how well it can collect light.
⢠Larger diameter = more light = clearer view
â Magnification
⢠Factors affecting the performance of
telescopes in magnifying objects vary
depending on the following:
â Availability of Light in the Environment
â Combination of Lenses/Mirrors Used
⢠Thickness and focal length
5. Parts of a Telescope
⢠Objective Lens â collects lots of lights and focuses it into a
very small image at the focus.
â˘Eyepiece Lens â magnifies the focused image into a size that
perfectly fits into the viewerâs eyes.
6.
7. Two Basic Types
⢠Reflecting ⢠Refracting
â An optical telescope. â Also an optical
⢠Increases apparent telescope.
brightness of object, and â Primarily uses lenses.
its angular size.
â Invented earlier.
â Invented in the 17th
Century.
â More used nowadays in
astronomical labs.
â Mirror based.
8. Refracting
Telescope
⢠Uses concave objective
and convex ocular lens.
â˘Bends parallel lights
into a focal point to
create a clearer image.
â˘Angular magnification is
equal to the ratio of
objective focal length over
eyepiece focal length.
â˘Used in binoculars.
9. â˘Pros:
â˘Low Maintenance
â˘Clear and contrasting Images
â˘Ease of Usage
â˘Cons:
⢠Chromatic Aberration
⢠Fringes or Rainbow like
appearances at the points of
the images where dark and
light colors appear.
⢠Because of the different
wavelengths in a white light.
â˘Costs more.
â˘Not developed for Astronomical
Purposes.
⢠Light loss.
10.
11.
12. Reflecting
Telescope
â˘Commonly uses parabolic
primary mirror and angled
flat secondary mirror to focus
light into the eyepiece.
⢠Famous models are
Gregorian ď First model built in
1688 by Newton.
and Newtonian telescopes.
â˘Easier to manufacture, Its popularity
increased with the
cheaper materials and less advent in silver
spherical abberations. coating, parabolic
mirror
manufacturing, seg
mented mirrors, etc.
13. â˘Pros
â˘Cheaper to manufacture
â˘More capable to detect faint
astronomical objects.
⢠Tends to have more compact
design.
â˘Cons
⢠The tube body can get easily
destroyed = high maintenance.
⢠Bulkier Design
â˘Spherical Abberation
â˘Higher magnification = smaller
field of view