basics astronomy 1.3

BASICS ASTRONOMY 1.3

Martin Crow Crayford Manor House Astronomical Society

Instruments


More on using the Planisphere a bit of practise.

Coordinate systems – locating objects.

The Constellations through the year.

Finding things on charts.

Last time


This week

About the use of binoculars.

Telescope types.

Finders, eye pieces, etc.

Setting up and using visually.

Types of mount.

The sky this week

About the use of binoculars


Adjusting focus and eye separation

Eye adjustment

Getting comfortable

The sky this week

Telescope types


Refractors

Telescope types


Refractors

Johannes Helvelius’s 8” Ariel telescope from 1673 had a focal length of 150 feet.

Amazingly a lot of sciencewas done using these typesof instrument but were madeobsolete by technical advances.

Telescope types


Refractors

The achromatic lens was first invented by an amateur optician Chester Moore Hall but John Dolland was granted a patent in 1758.

Telescope types


Refractors

The Apochromatic lens was inventedDolland’s son Peter in 1763.

Telescope types


Newtonian

Telescope types


Newtonian

A six inch diameter telescope was shown to the Royal Society in 1721 by John Hadley.

Built in late 1668 by Isaac Newton the mirror was made from Speculum metal.This first telescope had a mirror of just 1 1/3 “ but worked without colour distortionand could resolve the four Galilean moons and phases of Venus.A second version of this telescope was shown to the Royal Society in 1671.

The mirrors today are made from glass and the surface is Aluminised and are very efficient at reflecting light.

Telescope types


Gregorian

Invented and described in Optical Promota 1663 by James GregoryFirst built by Robert Hooke in 1673

Telescope types


Gregorian telescope of English manufacture circa 1735

Gregorian

Telescope types


Catadioptic – SCTs, Maks, Astrographs

Telescope accessories


Finder scope



Eye pieces



Barlow lens Star diagonals


Field flatteners

Dew bands

Coma correctors

Focal reducers

How to work out the magnification


F f

Magnification = F divided by f

Example: F = 500 f = 10 500/10 = 50

Telescope mounts


Alt Az mounts

Telescope mounts


Equatorial mounts

Telescope mountsEquatorial mounts

Telescope mounts

Setting up and using a telescope


Any questions


basics astronomy 1.3

Documents

ariel telescope

inch diameter telescope

royal society

apochromatic lens

achromatic lens

basics astronomy

magnification martin

john dolland