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From YouTube: SJAA Imaging SIG 8-21-18 ONAG Project
Description
San Jose Astronomical Association Imaging Special Interest Group Meeting held August, 21st, 2018 at Houge Park in San Jose, CA. Setting up an ONAG with focal reduction.
A
A
So
this
is
what
I've
been
imaging
with
for
the
last
year
or
so
and
prior
to
that,
the
same
motor
rig
was
on
my
8
inch
RC
and
that's
a
Rigel
systems
that
you
can
retrofit
on
here
with
the
gear
that
fits
on
behind
this
knob
will
talk
about
focal
reducers,
but
you
know:
I've
been
using
the
Astrophysics
ccd
t67,
it's
kind
of
a
standard
focal
reducer
that
people
use
with
these
with
these
RCS.
So
that's
what
focusing
and
focal
reduction
looked
like,
and
now
it
looks
like
this,
which
is
the
whole
talk
tonight.
A
So
this
is
a
moonlight
focuser
on
axis
guider,
from
innovation
for
sites,
there's
a
ZW
o
cooled
CMOS
and
a
filter
wheel
and
another
ZW
o
cooled
CMOS
for
the
guiding
camera.
So
we'll
go
into
all
of
that,
and
the
reason
that
this
is
on
the
very
first
slide.
Micrometer
is
because
all
the
measurements
and
everything
becomes
super
critical
when
you're
putting
something
like
this
together,
so
I
think
it
started.
So
we're
going
to
talk
about
back
focus
because
that's
critical
to
this
whole
thing.
A
What
that
means,
and
that
leads
us
into
focal
reduction,
also
touch
on
some
different
focus.
There:
options
for
this
particular
scope
in
others
and
then
we'll
get
into
the
actual
on
axis
guiding
device
right
here
with
the
cold
mirror
in
it
and
how
that
all
works.
How
that
came
together
with
my
need
for
focal
reduction,
then
some
results
that
I've
gotten
today
and
what
my
conclusions
are
and
then
I'll
give
a
parts
list
and
there's
also
an
appendix
with
a
bunch
of
other
stuff
that
came
up
during
this.
A
This
project
that
I
thought
would
be
interesting,
might
be
helpful
for
you,
guys,
okay,
so
it's
all
about
back
focus
when
you're
adding
stuff
to
your
imaging
train.
It's
all
about!
You
know
how
much
space
do
you
have
between
where
your
prime
focus
is
and
where
your
focus
er
is
able
to
place
your
imaging
rig.
So
we
need
to
look
at
focal
reducers
when
I'll
tell
you
why,
in
a
minute
and
then,
but
to
understand
that
we
need
to
understand
what
this
back
focused
thing
is.
A
So
all
of
these
these
are
sea
scopes
that
we
buy
come
in
various
brands,
right,
TPO,
GSO,
Astrotech,
orion
they're,
all
they
all
come
from
the
same
place.
They
come
from
the
same
factory
and
so
Jerry
how
many
extension
tubes
do
they
come
with
three
okay
Jerry
just
got
his
and
we
I'm
teasing
him
because
he
didn't
think
he
had
any,
but
he
had
three
like
he's
supposed
to
do
so
between
this
the
focuser
and
the
optical
tube.
A
They
have
usually
one
large
and
two
little
extensions
to
move
this
around
and
the
reason
for
that
is
to
come
to
focus
without
any
focal
reduction
or
any
other
nonsense
in
there.
You'd
need
that
focus
or
to
be
all
the
way
out
and
then,
as
you
start
to
add
stuff
back
in
especially
focal
reduction,
you'll
be
taking
those
extensions
out,
because
your
prime
focus
is
going
to
move
towards
the
OTA
so
which
is
what
I
just
said
yeah.
A
So,
as
you
add
stuff,
especially
the
focal
reducer
either,
because
you've
got
more
hardware
that
you
need
to
fit
in
there
or
because
you're
actually
moving
the
prime
focal
plane
with
a
focal
reducer.
You'll
need
to
move
that
focus
or
in
closer
to
the
to
the
OTA,
so
filter,
wheels
off
axis,
keiter
or
flip
mirror
focal
reducer
field
flattener.
A
All
that
stuff
has
to
fit
in
there
somewhere,
and
so
it's
also
possible
that
you
have
so
much
stuff
that
you
want
to
put
in
your
optical
train
that
you
actually
run
out
of
room
and
you
can't
come
to
focus
anymore
and
so
that
whole
thing
is
called
back,
focus,
okay
and
so
that's
most
likely
to
happen
with
focal
reduction.
Because
there
that's
again,
that's
actually
moving
the
focal
plane
towards
the
towards
the
optical
tube.
A
So,
let's
talk
about
focal
reduction
and
we'll
use
this
diagram
over
and
over
again
here
so
focal
reducers
they're
also
called
tella
compressors
focal
boosters
they're,
basically,
the
opposite
of
a
Barlow
right,
so
Barlow
you'd
want
to
use
for
planetary.
It's
going
to
magnify
things.
Focal
reducers
gonna,
do
the
opposite.
It's
going
to
spread
things
out
so
this
list
of
stuff
here
that
it
does
they're
really
all
the
same
aspect
right.
There
are
different
aspects
of
the
same
effect
right,
so
it's
gonna
make
your
scope
faster.
A
It's
going
to
reduce
the
focal
ratio
of
your
scope,
it's
going
to
shorten
the
effective
focal
length.
It's
going
to
increase
your
field
of
view.
It's
going
to
decrease
your
scopes,
image
circle!
It's
going
to
increase
your
image
scale,
in
other
words
arcseconds
per
pixel,
and
it's
going
to
decrease
your
exposure
time.
So
those
are
all
really
the
same
things,
but
that's
the
effect
of
a
focal
reducer
and
you
know,
I
showed
the
one
in
the
middle.
A
There
is
the
CCD
t67
which
most
people
use
on
these
scopes
and
then
the
one
on
the
here
I
can
use
my
new
toy.
Maybe
this
guy
is
the
the
one
that
I'm
using
in
here
now
that
Astrophysics
27
TV,
pH,
okay,
so
again
focal
reduction.
It's
a
positive
lens.
It's
going
to
shift
the
focal
plane
inward
towards
the
scope
and,
looking
at
this
chart,
you
see
the
the
reducer
right
there.
A
It's
going
to
shift
this
focal
plane
from
where
it
was
originally
in
towards
the
scope
and
the
way
that
you
control
how
much
focal
reduction
you
have
is
by
controlling
this
distance.
Here,
the
distance
between
the
can
or
sensor
and
the
focal
reducers
optical
center
that
controls
how
much
focal
reduction
you
have
then
adjust
that
then
the
things
that
change
are.
A
You
know
this
distance,
how
much
it
shifts
and
this
distance
where
the
focal
reducer
needs
to
be
for
things
to
come,
to
focus
and
also
then
the
the
effective
F
effective
focal
length
of
your
of
your
rig
okay.
So
why
would
we
want
to
do
this?
You
know
I
just
bought
this
big
scope
with
a
lot
of
magnification
or
what
have
you?
Why
do
we
want
to
then
change
the
optics
of
that?
So
as
an
example,
let's
look
at
my
latest
setup
here.
It's
the
12
inch
truss.
So
that's
the
12
inch
aperture.
A
Then
it's
a
native
focal
ratio
of
f/8
there's
the
focal
length.
It's.
They
don't
really
speck
the
image
circle,
but
most
sites
have
it
somewhere
between
30
and
35
millimeters
and
that's
kind
of
depending
on
you
know
it's
going
to
have
some
curvature
out
at
the
edges,
so
it
depends
on.
You
know
how
much
curvature
you're
willing
to
tolerate-
and
you
know
so.
Why
did
I
buy
this
scope?
A
Well,
I
bought
this
scope
for
the
aperture
and,
and
my
theory
was
that
it
would
help
me
with
imaging
from
a
light
polluted
place
like
Union
City,
where
I,
where
I
live.
Now
you
know
the
reason
I
buy.
The
RCS
is
for
the
aperture
per
per
dollar.
Basically,
so
I
have
trouble
with
the
French
Richie
Krejci
n.
It's
a
two
people
who
invented
this
particular
optical
design
and
what
what
this
optical
design
is?
It's
the
same
optical
design,
that's
used
on
the
Hubble
and
it's
got
basically
two
hyperbolic
mirrors.
A
So
there's
a
the
light
comes
in
and
it
goes
down
here
and
it
hits
the
12
inch
mirror,
which
is
a
hyperbola
and
that
reflects
up
here
to
a
secondary
mirror,
which
is
also
a
hyperbola,
and
then
it
goes
down
through
this
too,
but
I
out
the
back
and
your
camera's
out
here
somewhere.
So
the
light
actually
goes
through
there
three
times,
and
so
the
focal
length
of
the
scope
is
is
basically
three
times
it's
its
mechanical
length.
A
So
this
this
the
RC
is
shorthand
for
the
Ricci
crikey
on
and
it
refers
to
this
design
versus
a
Newtonian
or
Schmidt
Cassegrain
or
other
types
of
reflector
telescopes.
Alright.
So
if
we
then
look
at
what
camera
I
wanted
to
put
on
this
I'm
using
one
of
these
new
new
ish
cooled,
CMOS
cameras
as
ewo
a
si
1600,
and
so
it's
got
really
small
pixels
and
the
sensor
isn't
huge.
But
what
happens
is
if
we
use
this
CCD
cap
here,
there's
other
tools
that
you
can
use
to
do
the
math.
A
But
you
end
up
with
that
camera
and
that
scope
native
you
end
up
with
a
field
of
view
of
about
19
by
25
arc
minutes,
an
image
scale
of
32
arc
seconds
per
pixel,
and
we'll
note
that
that's
much
less
than
the
rule
of
thumb
of
one
arcsecond
per
pixel
that
you
need
to
have
good
sampling
in
what
is
typical
amateur
scene
around.
You
know
amateur
observing
sites
which
would
be
two
arc
seconds
per
pixel
if
you're
lucky.
A
So
what
and
the
other
thing
that
this
CCD
calc
does
for
you
is
it
gives
you
a
little
picture
here
with
the
fov
on
target
and
you
can
select
different
targets,
but
you
know
we're
all
familiar,
probably
with
m42,
so
I
put
that
there.
So
this
fov
is
okay,
it's
probably
a
little
on
the
small
side,
but
I
think
to
bigger
concerns
for
me
in
designing
this.
Was
you
know
one
this?
A
For
this
rig
so
again
using
the
focal
reducer
you
need
to
do
some
amount
of
planning
with
certain
focal
reducers
and
certain
scopes
like
with
SC
T's.
You
know
they
that's
a
whole
different
optical
setup,
with
the
moving
primary
for
focusing
the
focal
reducer
goes
on
the
back,
and
it
is
what
it
is.
It's
a
you
know
it's
a
certain
6.3
or
F
3.3,
and
you
can't
change
it
and
the
distance
from
there
to
your
sensor.
A
You
can't
change
and
that's
just
how
it's
set
up,
but
in
this
case
with
the
RCS,
you
can
control
how
much
reduction
you
get
again
by
that
distance.
Here
this
x1
distance
between
the
optical
center
of
the
reducer
and
the
focal
plane
of
the
imaging
sensor.
You
know
adjusting
that
controls,
then
how
much
this
thing
shifts
and
where
everything
lands-
and
you
may
run
out
of
back
focus
or
you
might
have
too
much
field
curvature
if
you
try
to
have
too
much
reduction,
so
I
keep
referring
to
this
chart
over
here.
A
So
this
is
a
web
page
and
you'll
notice
here
that
it's
on
my
hard
drive
it's
not
out
on
the
internet,
because
this
page
got
retired
at
some
point
guy
down
here
at
the
bottom.
It
has
copyrighted
it,
but
he
doesn't
it's
not
published
anymore.
So
I
used
the
Wayback
Machine
to
borrow
that
and
I've
I've
tweaked
it
a
little
bit
to
have
my
the
Scopes
I
use
and
the
focal
reducers
I
use
in
there
yeah
and
then
I've
also
added
some
some
more
parameters
in
the
in
the
output
all
right.
A
So
let's
do
an
example
so
still
not
worried
about
the
on
AG
or
any
of
that
stuff.
So
typically,
people
use
these
astrophysics.
C
CDT
67
s
with
these
with
these
RCS,
whether
it's
a
six
inch
8
inch
10
inch,
whatever
that's,
typically
what
they
use
so
again
using
CCD
calc.
Let's
say
we
wanted
to
do
a
0.7
X
action.
Now
we've
got
an
fov,
that's
quite
a
bit
larger
27
by
36,
and
we've
got
our
our
image
scale
up
to
0.46
arcseconds
per
pixel
and
we've
shrunk.
A
The
image
circle
down
to
closer
to
what
the
image
circle
of
the
of
the
censored
diagonal
is
so
we're
using
more
of
that
light
from
the
from
the
scope.
So
now
we've
got
an
effective
focal
ratio
of
F
5.6.
We
started
with
8
and
the
focal
length
in
changes
as
well,
so
you
could
go
for
more
reduction,
but
you're,
probably
going
to
start
getting
curvature
at
the
edge.
The
stars
will
start
to
stretch
out
into
the
corners
okay,
so
yeah
we're
still
over
sampling
by
quite
a
bit.
A
But
at
this
point,
if
we
wanted
to
have
that
rule
of
thumb
of
the
one
arcsecond
per
pixel,
approximately,
we
could
Bend
take
a
ray
of
2x2
pixels
as
one
pixel,
and
that
would
get
us
closer
to
that
number.
Depending
on
who
you
know,
I
gave
a
talk
a
couple
months
back
about
whether
you
should
or
shouldn't
been
with
it
in
this
situation,
with
CMOS
and
and
all
that,
so
take
your
expert,
but
either
way
I've
just
been
going.
Ben
1,
so
we've
talked
about
you
know
again
controlling
the
amount
of
reduction
with
the
spacing.
A
So
if
I
go
back
to
here,
you'll
see
that
it
says
that
x1
needs
to
be
90,
1.5,
millimeters,
okay,
but
that's
the
distance
from
the
optical
center
all
the
way
to
the
camera
sensor.
So
how
do
I
then
implement
that
in
the
real
world?
So
you
know
the
focal
reducer
itself
from
the
OTT
where
the
lens
is
in
here
to
the
threads
is
16
millimeters,
and
then
you
have
to
account
for
everything
else
between
that
and
the
camera
sensor.
So
the
zwl
filter
wheel
is
20
millimeters
and
the
flange
focal
distance.
A
That
means
the
distance
from
the
McKee.
A
nickel
front
of
the
camera
to
the
actual
sensor
is
six
point:
five
millimeters,
so
you
add
all
that
up
and
subtract
it
from
the
92,
and
it
turns
out
that
you
need
to
add
42
and
a
half
millimeters
of
or
it's
the
other
way
around.
You
need
50
millimeters
of
spacers
right
extension
tubes.
A
So
that
looks
like
that
and
then
even
with
all
those
three
extensions
that
I
was
teasing
Jerry
about
off
the
back
of
the
focuser
in
order
to
achieve
focus,
I
still
had
to
shove
that
whole
assembly
this
here,
where
it
says
sixteen
point
five
millimeters
is
right
about
here.
It
just
happens
to
be
facing
the
other
way
or
you
can
see
that
label
so
that
whole
thing
has
to
be
shoved
into
the
into
the
draw
tube
via
this
compression
ring.
You
know
to
about
there
in
order
to
achieve
focus.
A
So
if
I
had
any
more
focal
reduction
any
more
space
between
here
and
the
camera,
I
wouldn't
be
able
to
achieve
focus.
Unless
you
know
I'd
have
to
shove
this
in
even
further
I
guess
would
be
the
solution
there.
So
that's
leads
you
to
kind
of
well
what
about
thinner,
focusers
and
what
are
the
pluses
and
minuses
of
different
focusers.
So
you
know
this
is
the
stock
focuser.
It
doesn't
cost
anything
additional
other
than
the
three
hundred
fifty
dollars
to
do
the
motor
controller
solenoids
and
it's
got
a
fairly
low
profile.
A
It's
only
70
millimeters
and
then
this
moon
light
that
I
ended
up
with
in
its
narrow
and
its
thinnest
configuration.
This
is
actually
what
they
would
put
on.
A
SCT
edge
is
ninety
eight
millimeters
and
then,
if
you've
got
more
money
than
I
had
what
everybody
wanted
to
sell
me
was
an
optically
Oh
for
eighteen
hundred,
which
is
only
32,
millimeters
thick.
And
then
you
know,
if
you
really
wanted
it,
if
you
wanted
a
rotator
and
focuser,
then
you
can
get
your
wallet
out
for
for
that.
A
A
A
That
is
either
designed
for
your
scope
or
that
other
people
have
said
works
well,
so
I
would
suggest
you
know,
go
into
a
strobe
in
and
search
for
your
scope
and
search
for
that
focal
reducer
and
see
if
they,
if
anybody's,
using
that
combination
of
stuff
I
mean
the
way
I
picked.
My
first
equipment
was
looking
on
a
strobe
bin
and
you
know
I
had
an
idea.
You
know
I
thought
I
wanted
an
RC
which
don't
get
me
wrong.
I
mean
it's
bang
for
the
buck,
but
it's
also
as
a
first
scope.
A
It's
very
challenging
because
it's
got
such
a
long
focal
length
right.
So
other
people
would
argue
that
you
want
to
start
out
with
a
small,
refractor
and
everything's
less
critical.
You
got
a
much
bigger
field
of
view.
It's
easier
to
find
stuff,
it's
easier
to
track
all
that
stuff,
but
I
kind
of
jumped
I
didn't
want
to.
You
know
how
many
pictures
of
the
North
American
nebula.
Can
you
take
right
so
I
wanted
to
I
wanted
to
do
deep
space,
so
I
jumped
in
but
yeah
so
I
looked
and
saw.
A
Who
would
you
know
used
the
scope
I
was
interested
in
and
I
saw
that
they
were
using
the
CCD,
t67
and
I
saw
what
kind
of
images
they
were
getting
and
so
I
felt
pretty
comfortable
what
kind
of
mount
they
were
using
I
felt
pretty
comfortable.
That
I
should
be
able
get
some
good
stuff.
So
that's
one
way
to
do
it
all
right
anything
else
on
focal
reducers
or
back
focus,
okay,
yeah.
A
Bo
Gaston
Beaudette
at
the
last
to
AI
sees
Astro
imaging
conference
in
San
Jose,
and
it
was
really
intriguing
and
he's
doing
a
lot
of
interesting,
stuff
and
I
think
there's
there's
more
to
come,
but
it
all
rests
on
you.
Having
this
hardware
so
we'll
get
into
some
of
that.
So
what
is
this
thing
so
if
you've
ever
seen
a
flip
mirror?
So
a
flip
mirror
is
a
box
with
a
mirror
at
45
degrees
in
there.
A
So
it's
kind
of
like
a
diagonal,
but
a
flip
mirror
this
mirror
flips
up
or
or
down,
and
in
that
way
you
can
select
between
an
eyepiece
and
a
camera
or
between
two
cameras
or
two
eyepieces
or
whatever.
That's
a
flip
mirror.
So,
but
this
mirror
is
fixed,
but
it's
what's
called
a
cold
mirror
or
a
dichroic
beam
splitter.
A
So
what
it's
doing
is
it's
reflecting
the
visible
light
up
to
your
imaging
camera,
but
the
near-infrared
goes
through
to
your
guide
camera
and
because
that's
you
know
that
comes
in
two
sizes,
but
if
you
buy
it
based
on
your
image
circle,
so
you've
got.
You
know,
basically,
your
whole
image
circle
available
for
the
guider
versus
an
off-axis
guider,
where
you
just
have
a
little
pickoff
prism
or
something
that's
only
a
little
piece
of
your
your
field
of
view.
A
The
other
thing
that
happens
because
the
near-infrared
is
going
through
this
filter
at
a
45
degree
angle,
there's
some
astigmatism,
and
it
turns
out
that
there's
some
properties
of
that
that
you
can
take
advantage
of
to
to
do
autofocus
and
we'll
talk
about
that.
So
these
bullets
here
are
gas
tones
marketing
stuff
about
what
this
thing
does
for
you.
So
it
gives
you.
You
know
wide
field
of
view
for
your
guider.
It
does
have
the
nylon
white
plastic
screws
are
the
guiding
stage.
A
So
this
thing
does
move
around,
so
you
could
move
the
guiding
stage
to
select
a
guide
star
so
far
I
haven't
had
to
which
is
really
cool
and
then
I'm
hoping
it
remains
that
way,
because
I've
got
a
fairly
big
sensor
on
here.
It's
not
as
big
as
the
imaging
camera,
but
it's
fairly
big.
So
that's
an
advantage
over
off
axis
guiding
as
an
advantage
over
a
separate
guide
scope.
You
know
you
don't
have
any
differential,
flexure
you're,
looking
through
the
same
scope
that
you're
imaging
through
so
you're
guiding
what
you're
imaging
right.
There's!
A
No
there's
no
difference
in
alignment
or
you
know
flexure
as
things
change
over
the
night
angles
or
temperature
there's
some
advantages
to
guiding
in
near
infrared.
So
one
of
the
things
I
had
done
when
I
first
read
about
this
was
I,
went
out
and
got
a
near
infrared
filter
and
put
it
on
my
guide
camera
and
it
did
help.
Even
though
it
was
you
know,
a
separate
guide
scope,
it
does
seem
to
help
there's
less
high-frequency
noise
and
that
allows
you
to
image
lower
on
the
horizon
and
all
kinds
of
stuff
yeah.
A
So
he's
saying
you
don't
have
to
an
off-axis
guider,
you
might
have
to
rotate
everything
to
find
a
guide
star,
which
means
you
know,
you've
invalidated
your
flats
or
you
change
your
image
orientation
of
the
camera.
Maybe
you
don't
want
that.
So
in
this
case,
you
don't
have
to
do
any
of
that.
Depending
on
how
you
had
your
things
set
up,
you
know,
there's
no
filter
in
the
way
the
filter
wheel.
A
Here
is,
you
know
just
on
the
imaging
port
of
the
on
egg,
so
the
filters
are
not
in
the
optical
path
for
the
guide
camera.
What
else
and
then
he
talks
about
the
autofocus
which
we'll
talk
about
so
that's
happening
all
the
time
in
real
time.
It's
not
waiting
for
a
certain
temperature
for
a
filter,
change
or
anything.
It's
just
always
in
focus.
He's
got
some.
The
next
thing
that
he's
working
on
is
multi
star
guiding
so
rather
than
picking
a
guide
star,
it's
just
going
to
take
the
whole
frame.
A
Look
at
a
bunch
of
stars
so
that
you
don't
have
to
worry
about
picking
a
guide
star
at
all.
So
he's
got
that
software
out
in
beta.
In
fact,
it's
a
whole
imaging
suite,
but
you
can
buy
it
in
pieces.
You
can
buy
the
focus
piece
and
the
guiding
piece
and
the
imaging
piece
all
separately,
but
right
now
it
only
works
with
Maxim
DL,
which
I
don't
use,
and
so
they're
supposed
to
be
coming
out
with
a
new
version
that
works
with
sequence,
generator
Pro,
so
I'm
kind
of
waiting
for
that.
A
But
in
the
meantime
it
works
with
PhD
2.
So
again,
here's
what
this
looks
like
on
my
the
back
of
my
scope
in
my
yard,
so
the
full
frame
guide
star
using
pH
D
to
the
near-infrared
guiding
and
because
we
talked
about
that
light
passing
through
the
cold
mirror
on
an
angle.
You
get
this
astigmatism
which
changes
the
star
shape,
which
means
in
software.
You
can
look
at
that
star,
shape
and
figure
out
whether
you're
in
or
out
of
focus,
and
this
sky
guard
is
the
combination
of
the
guiding
and
focusing
software.
A
A
So
you
know
you're
you're
imaging
bouncing
off
that
mirror
the
visible
light
looks
normal,
but
if
you
look
at
it
through
the
guiding
port,
it's
going
to
have
kind
of
a
cross
shape
because
of
the
astigmatism
and
when
it's
out
of
focus
in
one
direction,
it
turns
into
a
sort
of
a
horizontal
line
when
it's
out
of
focus
in
the
other
direction,
it
turns
into
a
vertical
line.
So
you
can
use
that
he's
got
software
called
focus
lock,
that
is
from
optech.
A
Actually,
that
then,
can
connect
to
your
focuser
through
the
as
calm
driver
and
dynamically
adjust
that
all
night
long.
So
one
thing
I
didn't
do
research
carefully
enough
in
reading
all
the
manuals
ahead
of
time
was
there's
one
issue
that
you
can
have
a
problem
if
you've
got
a
large
Center
obstruction.
Well,
let's
see
I've
got
an
RC
with
the
50
scent
obstructed.
You
know
the
secondary's
covers
50%
of
that
mirror.
A
F6R
lower,
well
geez
I'm,
trying
to
do
focal
reduction
down
to
about
f6
and
I
added,
because
I
found
out
the
hard
way
if
you've
got
small
pixels.
That's
also
a
problem,
there's
also
kind
of
a
bit
of
a
catch-22
here
in
that
you
need
to
be
roughly
in
focus
in
order
to
get
guiding
going,
because,
if
you're
trying
to
guide
against
a
star
that
looks
like
that-
or
it
looks
like
that-
you're
not
gonna
get
very
good
guiding
right,
so
you
kind
of
have
to
be
close.
A
So
what
I've
been
doing
is
I
just
go
ahead
and
use
SGP,
auto
focus,
V
curve
to
get
me
there
and
then
turn
all
this
other
stuff
on
in
it
and
it
locks
it
in
and
keeps
it
there
the
rest
of
the
night
and
you
need
you
have
to
have
pH
D
to
running
and
guiding
in
order
for
the
focus
lock
to
get
its
image.
So
it's
actually
getting
its
image
of
the
guide
star
from
pH
D
2,
and
it
only
happens
when
you're
actually
guiding,
not
just
when
you're
looping.
A
So
you
have
to
keep
that
in
mind
as
well.
Okay,
so
let's
talk
about
some
challenges,
I
had
in
putting
this
together.
So
the
first
problem
is
that
everybody
wanted
to
sell
me
that
that
really
fancy
optic
leothinn
focuser-
they
didn't
want
to
talk
to
me
about
trying
to
get
it
to
work
with
the
stock.
Focuser
just
can't
be
done.
Another
gentleman
I
talked
to
was
convinced
that
I'd
have
horrible
vignette
ngey,
so
that
I
selected
and
you
know-
have
the
on
egg
SC,
which
has
t
two
openings
on
it.
A
So
it's
a
you
know
a
2.7
inch
wide
focal
reducer
going
down
to
42
millimeters
and
only
about
you
know
that
much
space
mechanically
optically.
It's
about
that
long
he's
like
there's
no
way
it
just
won't
work
and
I'm
like
I've
done.
The
math
and
I've
got
the
diagrams
and
he's
like
it
can't
work
so
anyway
that
was
that's
part
of
it,
and
so
just
adding
the
on
egg
by
itself
is
non-trivial
right.
There's
lots
of
measurements
that
you
have
to
take
and
lots
of
clearances
that
you
need.
A
You
know
what
happens
here
between
whatever
adapter
you
have
and
the
on
egg.
You
need
a
little
bit
of
space
there,
and
then
you
need
space.
If
you
want
the
guide
stage
to
be
able
to
freely
move
in
all
directions,
the
maximum
amount.
It's
designed
to,
then
you
need
some
space
between
the
top
of
the
on
egg
and
the
filter
wheel.
So
all
those
clearances
have
to
be
arranged
and
he's
got.
A
Gaston
has
some
very
confusing,
spreadsheets
and
and
some
web
pages
that
I
thought
were
also
confusing,
but
there's
lots
of
lots
of
that
that
you
have
to
go
through,
but
then
you
know
I
had
to
make
it
harder
by
wanting
to
do
focal
reduction
right.
So
the
way
they
expect
you
to
do
focal
reduction
is,
you
know,
put
a
focal
reducer
here
on
the
imaging
port
in
front
of
the
filter,
wheel
and
put
another
matching
one
here
on
the
guide
port
and
that
way
they'd
be
both
cameras
would
be
in.
A
You
know,
looking
at
the
same
thing
and
be
in
focus,
but
the
problem
with
that
is
you
know:
I
don't
have
the
back
focus
for
that,
because
the
on
AG
is,
you
know:
60
66,
68
millimeters
in
one
direction
and
ninety
millimeters
in
the
other
optically,
and
so
there's
not
that
much
space
with
the
focal
reducer.
You
know
the
on
egg
would
have
to
be
somehow
down
inside
the
the
focuser
or
something
right
remember
how
in
this
case,
the
focal
reducer
had
to
be
down
inside
the
focuser.
A
So
if
this
on
egg
was
on
the
front
of
the
focal
reducer,
you
know,
that's
not
obviously
not
going
to
fit
down
inside
there
and
then
so.
The
other
possibility
would
be
to
put
the
focal
reducer
with
the
on
egg
sort
of
in
the
middle,
so
you
could
put
the
focal
reducer
on
the
scope
side
and
then
you
know
the
on
egg
becomes
part
of
those
extension
tubes
between
your
imaging
camera
and
your
guide
camera.
A
So
the
problem
with
that
was
you
know
again
that
that's
68
millimeters
in
one
direction,
90
millimeters
in
another
compared
to
you,
know
50
millimeters
of
the
design
right.
So
the
on
AG
is
too
too
big
to
fit
with
the
focal
reducer,
so
I
had
to
find
a
different
focal
reducer
that
had
a
different
focal
length.
That
was
more
gentle.
That
would
allow
to
put
the
on
egg
in
that
space,
and
that
was
another
thing
that
you
know.
Oh
you
crazy.
You
can't
do
that.
A
A
You
know
so
I
found
this
thing,
so
some
challenges
with
that
it's
2.7
inch
threads.
So
you
know
it's
not.
You
couldn't
do
this
with
a
focus
or
smaller
than
three
inches
or
maybe
2.5
inches.
The
nose
of
this
thing
is
about
just
under
2.5
inches.
The
threads
are
2.7,
so
the
smaller
our
C's
8
inch
6
inch
would
not
work
with
this
focal
reducer
because
it
you
can't
get
it
down
inside
the
focuser
unless
you
replace
the
focuser
with
it
with
a
bigger
draw
tube.
A
So
that's
one
of
the
when
we
get
to
the
chart
again
the
the
webpage
that
does
the
design
that's
one
of
the
parameters
of
a
focal
reducers,
its
focal
length
and
its
diameter
of
the
optical
diameter.
Those
are
the
two
parameters,
so
it's
a
positive
lens,
so
it
has
a
focal
length
like
like
a
telescope
and
so
well
yeah.
Let
me
jump
all
the
way
back
here,
so
so
the
CCD
t67
is
305
focal
length
and
this
one
is
is
700.
A
Yes,
I
bought
the
focal
reducer
and
then
you
know,
I
had
I
had
gotten
talked
into
this
moonlight
focuser
and
in
its
stock
configuration
that
there
was
just
like
no
way
it
was
going
to
work.
It
was
just
too
tall
so
that
had
to
go
back
and
get
reconfigured,
and
then
also
you
know
there
was
an
adapter
that
went.
A
The
draw
tube
of
the
moonlight
is
68
millimeters
threads
and
the
adapter
to
go
from
that
to
the
astrophysics
2.7
inch
threads
they're,
the
only
ones
that
have
that
particular
standard
was
too
thick
to
wear
the
whole
design,
wouldn't
work
so
I
had
to
get
one
from
precise
parts.
That
was,
it
was
thinner,
so
speaking
of
which
so
now
I've
ordered
three
things.
A
So
it's
showing
you
here,
you
know
this
is
what
it's
going
to
look
like
and
and
if
you
click
on
this
guy
here,
you
get
a
3d
model
that
you
can
rotate
and
look
at
from
all
sides.
So
you
see
what
you're
getting
and
then
it
tells
you
what
the
optical
distance
is
going
to
be
and
what
the
price
is
is
going
to
be
so
and
then
it
takes
like
three
days,
and
you
have
your
you
have
your
part.
Only
downside
is
it's
pricey?
A
Incan
Vince
him
of
tracing
the
the
light
you
know
through
this
thing
to
show
that
I
wasn't
going
to
have
then
getting
and
he
he
said,
I,
don't
care,
it's
not
gonna
work.
So
here's
a
test
shot
that
I
did
with
the
spacing.
You
know
no
on
AG,
but
just
the
extension
tubes
between
that
new
focal
reducer
in
the
and
the
camera.
This
is
actually
a
four
panel
mosaic,
which
has
nothing
to
do
with
the
project,
but
it
was
just
something:
I
was
working
on
so
anyway
it
it
works.
A
So
then
you
know
this
is
where
you
know.
If
I
wanted
to
keep
the
moonlight,
everything
was
going
to
be
super.
Tight
I
was
only
going
to
have
a
millimeter
or
two
of
focus
left
inward
focus.
Inward
travel
on
the
moonlight
just
gonna
be
super
close
and
in
fact
you
know,
I
was
using
a
different
filter
wheel
with
different
filters,
and
I
have
two
other
filter
wheels.
Now,
at
this
point
and
they're,
both
thicker
than
this
one,
so
I
ended
up
having
to
go
to
make
this
all
work.
A
I
had
to
go
with
this
ZW
o
filter
wheel,
which
is
only
twenty
millimeters
and
I,
had
had
a
zwl
filter
with
filter
Rio
with
zwl
filters
in
it,
and,
as
some
of
you
may
know,
they
have
a
halo
problem
with
on
bright
stars
and
so
I
took
this
opportunity
to
replace
those
as
well
with
astronomic
six
nanometers.
So
at
that
point,
the
on
AG
or-
and
so
it
turned
out
that
it
was
still
too
close,
and
one
of
the
problems
was
this
mechanical
diagram
on
the
right
here
with
the
big
knot
sign
through.
A
It
is
wrong,
so
at
least
for
the
the
guide
camera
that
I
have.
Maybe
it's
an
older
model,
but
it's
completely
different
than
what
is
shown
here.
So
it's
flange
focal
distance
is
different.
This
is
showing
that
the
flange
screws
on
with
with
screws
mine
threads
on-
and
you
know
it's
it's
a
whole
different
piece
here
on
the
front
and
so
that
just
threw
everything
off
so
I
was
stuck.
A
I
was
bumming,
so
the
only
thing
I
could
do
at
that
point
was
to
put
a
guide
use,
a
smaller
guide
camera
that
would
fit
down
inside
the
helical
focuser
on
the
on
a
guide
port
here,
just
like
a
like
in
a
guide
scope,
and
so
I
grabbed
the
camera
from
my
external
guide
scope
and
put
it
on
there
and
then
face
the
next
challenge,
which
was
I
had
guide
stars
with
a
hole
in
the
middle,
even
when
they're
in
focus.
So
this
is
this
green
set
of
green
lights.
A
Here
is
telling
me
that
focus
lock
thinks
it's
info,
that's
the
best
focus
it's
going
to
get,
but
there's
this
hole
in
the
middle
of
the
star,
which
makes
it
very
confusing
for
PhD
to
to
do
good
guiding.
So,
apparently,
the
fix
for
that
is
to
reduce
the
amount
of
astigmatism
not
eliminated,
because
you
need
a
stigmatism
for
the
focusing.
A
But
you
know,
innovations
for
sight
will
sell
you
this
handy
little
lens
that
corrects
for
the
astigmatism
to
a
certain
degree,
and
you
can
adjust
it,
but
the
problem
is:
it
completely
fills
the
inside
of
that
helical
focuser,
which
meant
that
I
couldn't
then
use
the
camera
that
was
in
there,
so
I
was
still
stuck
it.
He
also
Gaston
had
me
using
at
that
point
because
of
this
hole
in
the
star,
a
special
version
of
PhD
2
that
apparently
they
didn't
adopt
his
his
alternate
algorithm.
A
A
So
I
can't
do
that.
So
what
do
I
do
so
you
know
I'm
sort
of
staring
at
this
for
a
long
time
and
then
I
figured
out
well
one
thing:
I
could
do
you
know
this?
This
is
the
back
side
of
the
help
to
fight
back
side
of
the
the
focal
reducer
here,
and
it's
got
this.
You
know
like
ten
millimeters
of
thread
depth
here
and
here's
my
adapter,
which
is
only
using
you
know
about
half
of
that.
A
A
You
know
hour-long
conversation
and
he
charged
me
for
a
half
hour
and
we
milled
off
7.9
millimeters
of
threads
off
that
thing
and
save
the
you
know
the
threads
were
still
viable
when
we
were
done,
which
is
good,
and
so
that
meant
the
on
AG
could
move
forward
by
that
almost
eight
millimeters
and
so
relative
to
the
on
AG.
Now
the
focal
planes
have
moved
out
by
almost
eight
millimeters,
which
allowed
me
to
then
achieve
focus
with
this
guide
camera
outside
the
the
helical
focuser.
Then
I
caught
another
break
when
that.
A
So
that
was
success,
and
so
this
I'll
talk
about
the
the
pixel
size
of
the
camera
in
a
minute,
but
so
success
yay
so
yeah
we
milled
that
thing
down
and
so
I
added
a
little
bit
of
space
between
the
filter,
wheel
and
the
imaging
port,
which
meant
that
now
I
could
have
everything.
Both
cameras
come
to
focus,
I
still
have
about
a
millimeter
and
a
half
of
focus
left.
Compared
to
this
is
my
critical
focus
zone,
so
I'm,
okay,
there
and
so
then
I
did
an
image.
A
So
here's
the
bigger
Crescent
there
is
when
I
did
from
Union
City
over
a
couple
nights
and
I
was
guiding
in
you
know
about
half
an
arc
second
RMS.
So
there
was
fifty
three
eight-minute
h.a
exposures,
47,
oh
three
and
then
I
put
some
RGB
stars
over
the
top.
So
look
at
that
one
and
then
compared
to
one
I
did
with
that
same
rig.
Now,
there's
lots
of
differences
between
these
two.
It's
not
good
science,
but
it's
the
same
rig
from
Scotts
Valley,
where
I
used
to
live,
which
is
darker.
You
know
so
shorter.
A
The
only
2.5
hours
total
integration
time
and
you
know,
they're
not
processed,
identical
blah,
blah
blah,
but
anyway,
I
think
the
new
one
looks
a
lot
better
and
we'll
go
into
some
some
metrics
and
that's
what
you're
supposed
to
see
right.
You're
supposed
to
see
you
know
both
the
improved
guiding
and
improved
focus
is
supposed
to
make
things
pop
you're
supposed
to
see
a
you
know,
more
detail
and
tighter
stars
and
everything
gets
get
gets
sharper.
So
we
will
come
back
to
the
guiding.
A
So
what
did
I
end
up
with
image
scale
wise,
so
we're
I'm
shooting
at
F
six
point:
three
I
keep
hitting
the
wrong
button.
F
six
point:
three
five
is
where
I
ended
up
and
here's
my
what
the
field
of
view
looks
like
I've
still
got
a
pretty
big
image
circle.
Now.
One
thing
I
learned
about
this:
this
these
calculations
here
is
this-
is
sort
of
a
back
calculation.
It
doesn't
really
have
anything
to
do
with
the
image
circle
of
the
telescope.
A
It's
just
telling
you
what
the
focal
reducer
is
gonna
do
relative
to
its
diameter,
so
I'm
still
kind
of
tweaking
that
part,
but
anyway,
so
guiding
results.
So
I've
noticed
I
have
like
super
huge
signal-to-noise
ratio.
Now
with
this
near-infrared
guiding,
you
know
it's
typically
like
around
200,
which
is
crazy.
You
know
you
see
these
stars
and
you
don't
see
any
noise
at
all.
It's
just
boom
and
I
haven't
had
to
move
the
guide
stage
so
now,
I
think
I've
done
three
or
four
targets
and
I
haven't
had
to
move
the
guide
stage.
A
So
that's
good!
You
know:
I
passed
the
log
to
the
PhD
two
guys
when
I
was
working
with
that
hole
and
the
star
thing,
and
they
declared
that
hey,
you
know
you're,
you
should
stop
stressing
your
Guiding
is
probably
seen
limited
at
this
point
right,
and
so
you
know
I'm.
Looking
at
this
and
I'm
very
happy
with
you
know
my
RMS
here
this.
This
is
not
good
and
then
in
looking
at
the
analyzing,
the
the
log,
you
know
there's
some
stuff
that
could
be
cleaned
up
with
periodic
error
correction.
A
A
That's
a
salt
problem,
in
my
view,
right
I'm,
not
gonna,
I'm,
not
gonna,
worry
about
guiding
any
more
on
that
and
then,
as
far
as
autofocus
goes
so
these
are
this.
Is
you
know
again
the
focus
locks
view
of
the
guide
star
when
it's
in
focus
and
now
I
noticed
the
hole
is
not
so
bad
anymore.
That's
because
I
have
bigger,
pixels,
I,
think
and
then
it
has
these
charts.
A
That
is
really
for
troubleshooting.
When
you
have
problems,
I
guess
so
these
are
guiding
frames.
So
I
was
guiding
at
three
seconds.
So
each
you
know
a
hundred
times.
Three
seconds
would
be
the
time
period
there.
So
you
can
see
it
when
it's
initially
adjusting
and
then
over
the
night.
It's
making
changes,
and
these
were
two
different.
Two
different
nights,
different
situations
so
and
then
so
what
are
the
focus
results
so
using
a
couple
different
tools
here?
A
This
is
Fitz
image
grader
at
the
top,
so
I've
got
you
know
pretty
much
seen
limited
focus
there
and
really
small
deviations.
So
that's
good
and
the
pics
insight
is
telling
me
the
same
thing.
This
is
the
the
full
width
half
max,
except
for
some
clouds
and
I
know.
These
are
clouds
because
of
my
cloud
sensor
project
and
then
the
the
deviation
is
also
small
in
pics
insight.
A
So
this
was
cross
multiple
nights,
different
target,
altitudes
air,
mass,
etc.
It's
holding
the
holding
the
focus
another
way
to
look
at
that
and
again,
you
know
this
is
not
good
science,
but
comparing
those
two
images,
they're
processed
images,
so
kind
of
all
bets
are
off,
but
if
I
just
pick
a
star
same
star
in
both
so
before,
I
was
doing
SGP
autofocus
and
that
2.5
hours
from
Scotts
Valley
the
star
profile,
looks
like
this.
It
thinks
the
scene
was
pretty
bad
at
almost
12
arc
seconds.
A
A
Then
I
wanted
to
just
understand.
Why
was
it
making
those
adjustments
over
the
night
was
a
temperature?
What
was
it
and
so
I
graphed
it,
and
these
air
bars
represent
the
critical
focus
zone
and
they
really
could
be
twice
that
big
right
because
I
this
is
the
whole
critical
focus
zone.
So
you
could
argue
that
it
could
be
off
on
one
side
of
critical
focus
by
the
whole
amount,
so
I
could
have
made
those
bigger,
I
guess,
but
anyway
there's
you
know
it's
kind
of
a
rough
correlation
to
temperature
right.
A
So
this
is
the
ambient
temperature,
and
this
is
the
focus
position.
So
then
I
looked
at
some
other
parameters
and
it's
kind
of
interesting
that
there
seems
to
be
kind
of
two
groups
of
data
in
all
these
charts
and
it's
basically
on
either
side
of
the
meridian.
So
my
conclusion
is:
there's
something
in
my
scope:
that's
that's
shifting
a
little
bit
when
it
flips
does
the
Meridian
flip.
There
seems
to
be
some
some
weak
correlation
here
with
the
mass
but
I.
Don't
know
not
enough
data,
but
point
is
it's
in
good
focus?
A
So
what
are
my
conclusions?
So
I
got
seen
limited
guiding
with
no
need
to
move
the
guide
stage,
at
least
so
far
for
the
targets
I've
I've
looked
at
I've
got
consistent,
sharp
focus
when
I
made
this
slide.
I
said
I
was
going
to
go
back
and
check
it
with
a
baton
off
mask
which
I
did,
and
it
actually
made
it
worse.
So
the
V
curve
in
s
GP
turned
out
to
be
a
better
way
to
do
it.
A
So
that's
the
technique,
I'm,
using
with
the
moonlight
temperature
sensor
I
also
have
my
sky
sensor-
has
an
ambient
on
it
as
well,
but
I
just
used
two,
because
the
the
one
on
a
focal
reducer
ends
up
in
the
fits
header.
So
it's
easier
to
do
that.
So
you
know
it
would
have
been
easier
to
have
a
thinner
focuser.
So
if
I
could
have
thrown
more
money
at
this
decided
to
live
with
the
stock
focuser,
then
things
wouldn't
have
been
quite
so
critical,
but
overall
I
think
it
was
worth
it.
A
The
cost
and
the
effort
I'm
very
happy
with
the
results,
so
that
is
that
and
I've
got
some
more
information
here.
So
second
image
I
just
posted
this
today,
it's
a
little
corner
of
Pickering's
triangle
or
another
way
to
say
it
is
it's
a
very,
very
small
piece
of
the
veil
nebula,
but
anyway,
I
just
thought
that
was
cool
I
might
do
a
mosaic
or
something
but
anyway,
so
that's
another
by
color
and
then
RGB
stars
over
the
over
the
top
so
parts
right.
So
the
for
the
12
inch
trust
RC.
A
We
had
the
moonlight
focuser
for
large
RC
with
the
high-rez
stepper
motor.
It
comes
with
a
mini
v2
controller,
except
that
they
reconfigured
it
with
these
options
to
make
it
as
small
as
possible.
Then
I
needed
the
precise
parts
adapter
to
go
from
that
draw
tube
to
the
Astrophysics
focal
reducer.
On
the
other
side
of
the
Astrophysics
focal
reducer,
we
shaved
7.9
millimeters
off,
and
then
we
had
of
a
precise
parts
adapter
to
go
to
t2.
A
It
goes
into
the
on
egg,
then,
on
the
imaging
side,
a
spacer,
the
filter,
wheel
and
the
camera
of
the
imaging
camera
and
on
the
and
I
have
both
monochrome
and
one
shot.
Color
cameras
that
I
can
swap
here
and
then
the
ASI
174
cooled
on
the
guide
port
and
it
turns
out
that
you
know
those
bigger,
pixels,
helped
and
I
didn't
have
to
get
that
astigmatism.
A
So
I'm
gonna
pause
for
breath
again,
so
I
have
some
other
stuff
to
talk
about,
but
any
questions
about
the
the
on
egg
or
anything,
we've
talked
about
so
far
yeah.
So
originally
the
filter
wheel
that
I
had
planned
on
using
originally
so
I
have
other
filter
wheels.
So
I
have
a
filter,
wheel,
that's
2,
inches
and
has
Bader
narrowband
in
it,
but
it
it
only
has
four
positions
and
then
I
have
a
CW.
A
Oh,
it's
got
el
RGB
and
narrowband,
but
it's
only
got
7
positions
and
anyway,
my
thinking
was
that
I
I
couldn't
use
the
filter
wheel
with
the
color
camera.
So
I
was
going
to
replace
the
optical
space
of
the
filter
wheel
when
I'm
using
the
one-shot
color
with
a
spacer
and
I
started
to
do
that.
The
other
night-
and
you
know
that
meant
I-
was
going
to
have
to
refocus
and
everything
and
then
I
realized
that
well
there's
an
empty
filter
position
in
this
filter
wheel.
So
I
could
just
shoot
through
that.
A
In
theory,
the
camera
would
thread
on
to
the
same
exact
position
as
the
other
camera,
which
turns
out
not
to
be
true
but
think
you
still
have
to
refocus
but
but
close.
But
then
I
also
realized
that
you
know
any
time
you
go
through
glass.
It
does
shift
your
focal
plane
a
little
bit
so
I
decided
to
just
shoot
through
the
luminance
filter,
which
is
roughly
the
same
thickness
as
the
narrow
band
filters.
A
So
that's
what
that
was.
It
doesn't
have
anything
to
do
with
the
infrared.
It's
because
I
had
one
and
it
turns
out
in
PhD
two
in
the
latest
versions
and
they
might
have
to
be
dead
versions,
but
you
can
control
the
camera
because
I
didn't
that's
another
thing.
I
hadn't
thought
about.
Oh
I've
got
a
cold
camera,
but
I
didn't
think
about
how
am
I
gonna
turn
it
on.
So
you
have
to
have
some
software
to
control
it
right.
A
So
that's
now
in
PhD
2,
so
that
there
is
and
I
think
it's
in
the
appendix
there
is
a
mini
version
of
that
same
camera
that
would
have
fit
in
inside.
But
it's
it's
not
cooled
and
again.
I
thought
I
was
needed
to
be
outside
because
of
that
astigmatism
thing
so
and
yeah
I
didn't
want
to
buy
another
camera
too.
So
this
camera
will
also
it's
a
very
good
planetary
camera.
A
Although
I
don't
haven't
done
a
lot
of
planetary,
but
that's
the
reason
why
this
camera
exists,
but
it
it
selected
that
for
guiding
not
just
because
I
had
it,
but
because
excuse
me,
the
pixels
are
there
five
point:
eight
something
microns,
so
they're
bigger
you
kind
of
need
that
and
it's
a
it's
a
fairly
it's
not
as
big
as
the
imaging
sensor,
but
it's
a
fairly
big
sensor
compared
to
a
typical
guide
camera.
So
otherwise,
if
you
have
too
small
a
sensor,
then
you're
going
to
be
moving
the
guide
stage.
A
All
over
the
place
which,
when
I
was
using
that
qhy
camera
you
know
there
was
never
more
than
one
guide
star
in
the
in
the
field
of
view,
but
I've
been
using
it
with
the
near
infrared
filter
all
along.
So
so,
I'll
put
the
the
focal
reducer
calculator
up
there
still
tweaking
the
the
image
circle
piece,
I
guess,
but
because
the
way
it
is
at
this
URL
is
actually
the
wrong
direction
that
the
way
the
guy
had
it
originally
I
noticed.
As
I
said,
the
latest
PhD
at
least
the
dead
versions,
can
control
camera
cooling.
A
If
you've
got
a
cooled
camera
it's
in
on
the
brain.
Under
the
camera
specific
information
at
the
bottom,
you
can
have
a
set
temperature
and
either
on
or
off
so
as
Bruce
advised
me.
You
probably
don't
want
your
camera
cooler
running
during
the
daytime,
so
you
could
have
SGP
disconnect
all
the
guiding
devices
when
the
sequence
ends
and
that
would
shut
the
cooling
off
at
the
end
of
your
sequence.
A
So
one
of
the
learnings
from
this
whole
thing
with
the
stock
focuser
was
nobody
knew
that
there's
an
adapter
sitting
here
between
the
compression
ring
and
the
draw
tube.
Nobody
knew
that
came
off.
I
just
thought.
This
was
one
piece
and
what
that
means?
Is
it's
technically
possible
to
put
something
like
that?
27
tv
pH,
focal
reducer
in
here
it
wouldn't
fit
through
here
and
so
I
did
buy
another
precise
part,
it's
just
on
this
side,
just
to
store
it.
A
So
now
precise
parts
knows
about
that
and
they
know
what
the
threads
are
and
they
can
build
adapters.
So
if,
for
some
reason
you
want
to
do
something
with
the
draw
tube
of
your
big
RC
stock
focuser,
you
can
now
do
that
with
precise
parts.
I
had
hope
these
threads
look
like
they
might
even
be
that
Astrophysics
2.7,
but
they're,
not
that
they're
close
but
closest
led
to
that
discussion.
A
Where
the
guy
said
now,
if
you
try
to
thread
that
in
there
you're
gonna
screw
up
the
threads
and
don't
try
to
return
the
return
it
to
me,
so
all
right,
what
else
yeah
so?
Yes,
there's
a
mini
version
of
that
camera.
I'm
aware
that,
but
you
know,
I
was
had
those
challenges
with
the
thought.
I
needed
the
astigmatism
thing.
I
at
one
point
was
wanting.
A
You
know
like
a
helical
focus
or
on
this
side
on
the
imaging
port
and
did
research,
and
there
are
helical
focusers
that
don't
rotate
and
there's
one
that's
11
to
18
millimeters
is,
is
the
thinnest
one
I
could
find,
which
is
still
way
too
thick
for
this
project.
But
if
you
had
a
thinner,
focuser
and
had
more
room
to
move
things
around,
it
might
be
a
handy
thing
to
add
in
so
just
FYI,
then
another
thing
I
noticed
regarding
camera,
cooling
and
whatnot
was
I
had
never
scrolled
down.
A
Phd
to
this
window
here
was
always
cut
off
and
I
had
never
bothered
to
scroll
down
to
see
all
this
information
that
that
they
had
here.
So
it's
got
your
image
size
and
your
field
of
view,
and
then
the
camera
cooler
information
at
the
bottom,
so
I
just
redid
my
UI
to
have
that
displayed
all
the
time.
So
that's
what
it
looks
like
now
there
and
then
what
else
did
we
learn?
So
in
rebalancing
the
scope,
you
know
the
scope
got
lighter
so
eyes,
moving
the
counterweights
up
and
I
thought
well
geez.
A
Maybe
I
can
get
away
with
two
counterweights
instead
of
three
and
I
wonder
what
the
better
situation
is
and
kind
of
I
thought.
I've.
Always
thought
turns
out
incorrectly
that
less
weight
on
the
Mount
in
total
would
be
a
good
thing,
so
I'd
rather
have
fewer
counter
weights
out
at
the
end
of
the
counterweight
bar.
This
is
assuming
the
counterweight
bar
doesn't
flex,
which
is
also
not
the
case,
seemed
like
it
would
be
a
better
idea.
A
Let
me
just
let
me
just
post,
you
know
so:
I
posted
on
cloudy
nights,
hey
what's
the
best
thing
and
then
got
back
this
whole.
You
know
like
six
guys
pointing
to
different
references
all
in
agreement
and
all
saying
that's
wrong.
You
want
the
counter
weights
up
as
high
as
possible
because
it
has
to
do
with
the
moment
arm
or
let
me
let
me
get
it
right
here.
It's
not
the
you
know.
A
I
was
just
thinking
about
the
force
arm,
but
they're
talking
about
the
inertial
moment
arm
because
it
has
to
do
with
the
distance
squared.
So
basically,
what
you
want
to
do
is
you
want
to
have
more
counter
weights
and
you
want
to
have
them
up
as
high
as
possible,
so
that
they're
suggesting
that
you
put
your
counterweights
all
the
way
at
the
top.
A
If
you
had
this
situation
so
who
knew
right
so
at
that
step,
where
I
rebalanced
and
my
guiding
got
better,
maybe
part
of
it
was
because
of
moving
the
counterweight,
so
I
have
since
ordered
some
more
counter
weights
and
will
continue
to
push
mine
higher
and
see
if
it
but
I
have
to
keep
reminding
myself.
That
guiding
is
really
a
solved
problem
now,
so
I
should
stop
trying
to
make
it
better.
But
anyway
there
you
have.
It
okay,
then
one
more
thing.
So
this
is
a
little
off
topic,
I
guess
well
for
the
on
egg.
A
But
another
thing
that
came
up
was,
you
know:
let's
say:
you've
got
Dec
backlash
that
you
can't
fix
in
your
mount,
so
you
know
and
I
had
different
people.
Looking
at
my
guiding,
so
gaston
dr.
dr.
Beaudette
was
saying
yeah,
you
want
to
just
miss
polar
a
line.
A
little
bit
that'll
force
you
to
guide
Dec
in
one
direction.
Only
well
and
so
I'm
like
well,
ok,
miss
align
by
how
much
I
mean
in
what
direction,
and
so
I
wrote
to
the
PhD
two
guys
and
they're
saying
yeah.
They
gets
this
one.
A
Oh
it's
here
he's
saying
yeah.
It
doesn't
matter
which
direction
just
a
small
error,
a
couple
arc
minutes
and
then
increase
your
your
men
move.
So
those
are
things
that
you
could
try
if
you've
got
a
problem
with
backlash
and
I.
Think
I
had
a
follow-up,
oh
yeah,
because
then
he
says.
But
if
you
are
misaligned
by
too
much,
then
you
have
field
rotation.
Okay.
So
how
much
is
is
too
much
so
then
there's
you
know
websites
that
do
that
calculation
and
stuff
for
you
too,
so
that
that
information
is
in
here.
A
Although
I
didn't
end
up
following
up
on
it
because
again
guiding
became
a
solved
problem.
Ok,
yeah
it
doesn't
matter,
apparently.
So
what
I
did
when
I
rechecked
my
polar
alignment
with
a
pole
master
it
at
where
it
says
press
Start
monitor,
so
it's
roughly
aligned
and
then
you
go
in
to
the
fine-tuning.
So
in
the
fine-tuning
step,
it
was
just
at
the
outside
of
that
circle
where
it
wants
you
to
put
things
together,
so
it
was
just
it's
and
then
PhD
2
was
in
guiding
assistant
was
telling
me
that
it
was
one
point.
A
Seven
two
point
one
arc
seconds
off,
but
if
you
look
at
my
and
I
I
did
mess
around
a
little
bit
with
the
min
move,
but
it
didn't
it
just
made
things
worse,
so
I'm
guiding
in
Dec
changing
directions
and
I'm
still.
You
know
this
one
says
point
four
one
arc
seconds
of
RMS
I'm
not
going
to
mess
with
it.
The
only
thing
I
know
is.
A
He
said
because
it's
doing
it
at
an
angle,
that's
all
I
know,
don't
claim
you
do
not
get
yeah
I,
don't
know,
I
mean
we
could
go,
look
and
see
from
my
memory.
That's
all
that's
all
he
says
is
because
it's
coming
through
at
a
45
degree
angle,
the
image
parts
reflecting
off
the
the
surface
and
the
guiding
is
going
through
a
lens,
essentially
at
a
45
degree
angle
did
I
measure
I,
don't
know
how
to
do
that.
There's
a
that.
A
Astigmatism
corrector
has
some
numbers
associated
with
the
three
different
settings:
I,
don't
remember
what
those
numbers
are.
If
you
go
to
innovation
for
sites,
he's
got
some
education
pages
where
he
goes
through
all
this
stuff,
but
I
don't
know
if
you're
gonna
get
the
level
of
detail,
but
you
can
certainly
email
it.
So
what
I've
been
doing
is
I.
Do
I
turn
the
focus
lock
off
I
do
a
V
curve
and
with
typically
with
H
alpha,
because
I
figure,
that's
the
most
important
thing
for
me
right
in
SGP
and
note
down
the
focus
position.