Telescope Basics; Focusing; Image Orientation; Calculating Magnification - SKY-WATCHER LightChariot 80AR-AZ Instruction Manual

TELESCOPE BASICS

A .telescope .is .an .instrument .that .collects .and .focuses .light. .The .nature .of .the .optical .design .determines .
how .the .light .is .focused. .Some .telescopes, .known .as .refractors, .use .lenses. .Other .telescopes, .known .
as .reflectors, .use .mirrors. .The .LightChariot
an .objective .lens .to .collect .its .light. .The .LightChariot
secondary .mirror .to .gather .and .focus .light. .

Focusing

Once .you .have .found .an .object .in .the .telescope, .turn .the .focusing .knob .until .the .image .is .sharp. .To .focus .
on .an .object .that .is .nearer .than .your .current .target, .turn .the .focusing .knob .toward .the .eyepiece .(i.e., .so .
that .the .focusing .tube .moves .away .from .the .front .of .the .telescope). .For .more .distant .objects, .turn .the .
focusing .knob .in .the .opposite .direction. .To .achieve .a .truly .sharp .focus, .never .look .through .glass .windows .
or .across .objects .that .produce .heat .waves, .such .as .asphalt .parking .lots.

Image Orientation

The . image . orientation . of . any . telescope . changes . depending . on . how . the . eyepiece . is . inserted . into . the .
telescope. .When .observing .through .the .LightChariot
side . up, . but . reversed . from . left . to . right. . When . observing . straight . through, . with . the . eyepiece . inserted .
directly .into .the .telescope, .the .image .will .be .inverted. .
F
Original object orientation
When .observing .through .the .LightChariot
down .when .looking .through .the .eyepiece.
For .astronomical .viewing, .out .of .focus .star .images .are .very .diffuse, .making .them .difficult .to .see. .If .you .
turn .the .focus .knob .too .quickly, .you .can .go .right .through .focus .without .seeing .the .image. .To .avoid .this .
problem, .your .first .astronomical .target .should .be .a .bright .object .(like .the .Moon .or .a .planet) .so .that .the .
image .is .visible .even .when .out .of .focus. .

Calculating Magnification

You .can .change .the .power .of .your .telescope .just .by .changing .the .eyepiece .(ocular). .To .determine .the .
magnification .of .your .telescope, .simply .divide .the .focal .length .of .the .telescope .by .the .focal .length .of .
the .eyepiece .used. .In .equation .format, .the .formula .looks .like .this:
. .
. .
. .
Let's .say, .for . example, . you . are . using . the . 25mm . eyepiece. . To . determine .the . magnification . you . simply .
divide . t he . f ocal . l ength . o f . y our . t elescope . ( for . e xample, . t he . L ightChariot
by .the .focal .length .of .the .eyepiece, .25mm. .Dividing .910 .by .25 .yields .a .magnification .of .6.4 .power. .
0
Reversed from left to right,
as viewed with a Diagonal
. . . . . . Focal .Length .of .Telescope .(mm)
Magnification . .= . . . . . .
. . . . . . .Focal .Length .of .Eyepiece .(mm)
.80 .and .102 .telescopes .are .refractor .telescopes .that .use .
™
.10 .is .a .reflecting .telescope .with .a .primary .and .
™
.80 .or .102 .using .a .diagonal, .the .image .will .be .right .
™
F
Inverted image, as viewed
with the eyepiece directly
.10, .a .reflecting .telescope, .the .image .will .appear .up-side-
™
in telescope
. 8 0 . h as . a . f ocal . l ength . o f . 9 10mm) .
™
FIG. 10