Operation Manual

34
TELESCOPE TYPES AND OPTICAL SYSTEMS
Morethan3centuriesago,GalileoGalileidirectedasmalltelescopetowardthestars,andthe
modern age of the science began.Thereare two main groups of telescopes: terrestrial tele-
scopesandastronomicaltelescopes.Themaindifferenceisthattheterrestrialtelescope,which
is intended for seeing objects on the Earth, providesan upright or normal image, while the
astronomicaltelescopeprovidesarotatedimagethatstandsonitshead.Whileitisimportant
forEarth-boundobjects,toseethemintheirnormalposition,forastronomicalobservations,this
isnotimportant.
Thereasonthatastronomicaltelescopesgenerallyshowareversedimageisthat,in contrastto
terrestrialtelescope,theypossesnospecialisederectinglenssystem.Althoughtheadditionallens
systemprovidesanuprightimage,itcausesaslightlossoflight.Inanastronomicalthatisusedfor
extremelyweakobject,itisimportanttoreducethelossoflighttoaminimum.Thisdoesnotmean
thattheterrestrialtelescopescannotbeusedforastronomicalobservations.Theyareonlynotable
toshowaweakobjectaswellasanastronomicaltelescope.

Astronomicaltelescopesarefurthermoresplitintotwocategories,whichdependontheoptical
systemused.Therefractoronlyuseslensesformagnification,whilethereflectorusestwomir-
rors,inplaceofthelenses.
Objective lens
Eyepiece
Galileo telescope system
Telescope
Objective lens
Objective lens
Eyepiece
Eyepieces
Eye
Eye
Astronomical telescope system
Telescope system for Earth observation
Eye
Eyepiece
Telescope
Objective mirror
Deection mirror
Newton mirror telescope system