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Celestron SS80 User Manual

Celestron SS80
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Figuring
Magnification
(Power)
You
can
change
the
magnification
of
your
spotting
scope
simply
by
changing
the
eyepiece
(also
called
an
ocular).
To
determine
the
magnification
with
your
spotting
scope,
simply
divide
the
focal
length
of
your
spotting
scope
by
the
focal
length
of
the
eyepiece.
In
equation
format,
the
formula
looks
like
this;
Focal
Length
of
Spotting
Scope
(mm)
Magnification
--
Focal
Length
of
Eyepiece
(mm)
For
example,
to
determine
the
magnification
of
the
C90
with
a
lOnun
eyepiece,
divide
the
focal
length
of
the
C90
(l(X)0mm)
by
the
focal
length
of
the
eyepiece
(10mm).
1000
divided
by
10
yields
100
power.
Although
the
power
is
variable,
each
instrument
has
a
limit
to
the
highest
useful
magnification.
The
general
rule
is
that
60
power
can
be
u^
for
every
inch
of
aperture.
For
example,
in
a
3.5"
diameter
spotting
scope,
such
as
the
C90,
the
maximum
useful
magnification
is
210
power.
This
is
derived
from
multiplying
60
times
3.5.
Although
this
is
the
maximum
useful
magnification,
most
observing
is
done
in
the
range
of
20
to
35
power
for
every
inch
of
aperture.
Field
of
View
Determining
the
field
of
view
is
important
if
you
want
to
get
an
idea
of
the
size
of
the
object
you
are
observing.
To
calculate
the
actual
field
of
view,
divide
the
apparent
field
of
the
eyepiece
(supplied
by
the
eyepiece
nwnufacturer)
by
the
magnification.
In
equation
format,
the
formula
looks
like
this:
Apparent
Field
of
Eyepiece
True
Field
(in
degrees)
=-
Magnification
Using
the
example
we
started
with
in
the
previous
section,
we
can
determine
the
field
of
view
using
the
same
10mm
eyepiece.
The
10mm
eyepiece
has
an
apparent
field
of
view
of
46®.
Divide
the
46®
by
the
magnification,
which
is
100
power.
This
yields
an
actual
field
of
.5®,
or
about
half
of
a
degree.
To
convert
this
to
feet
at
one
thousand
yards,
multiply
the
actual
field
of
.5®
by
52.4.
This
gives
us
a
field
width
of
24
feet
at
one
thousand
yards.
SS80IC90
21

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Celestron SS80 Specifications

General IconGeneral
BrandCelestron
ModelSS80
CategoryTelescope
LanguageEnglish

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