Original subtitles

have you ever wanted to be a time

traveler

this is a photo i took last night of the

andromeda galaxy a barred spiral galaxy

made up of one trillion stars

this galaxy is one of the closest

neighbors to our milky way galaxy which

is why it looks so large in the sky

but it's still two and a half million

light years away from us

that means this photo is a snapshot of

what the galaxy looked like

two and a half million years ago because

that's how long it took the light to

reach us here on earth

so in a sense time travel is already

possible

and if you have a camera a telephoto

lens

and a tripod you too can be a time

traveler

and i'm about to show you how

[Music]

hello my name is nico carver and i'm an

astrophotographer

astrophotography is the art of

photographing the night sky

and i have a particular interest in

photographing deep sky objects meaning

objects outside of our solar system

today i'm going to show you every step

of how to capture and process

a photo of the andromeda galaxy before

we get started i just want to very

quickly say that this youtube channel is

supported by my patrons over on patreon

if you'd like to join it starts at just

one dollar a month and i truly

appreciate the support

let's dive right in what do you need to

take a photo like this

well the first important thing is a dark

sky

i live in boston so i knew i had to

escape the city lights to take this and

i drove about

two hours away to a park with much

darker skies

the best place to find a dark location

near you is a website it's called

light pollution map dot info and on this

website the cooler colors like green

gray and black mean darker skies

if you aren't sure where you can set up

i'd start with local astronomy clubs who

often have their own

fields for club members another idea is

to talk to park departments and

campgrounds because a lot of times you

might be able to get permission to be in

a park after hours

or a campground may have a nice field

you can use the second thing needed to

take a photo like this one is a bit of

time

both for planning and for practice

astrophotography is a pretty technical

form of photography meaning it does take

a bit of practice with your camera

and planning the settings you're going

to use to get good results

the third important thing for taking a

photo like this one is equipment

and you may think you need a really

fancy tracking mount and a telescope to

take a photo like this

but it actually was done with this

equipment you're seeing right here

everything that i used to take this

photo i spent under a thousand dollars

i did buy some things used but it's

definitely

possible on an even tighter budget and

if you don't already have this stuff

maybe you can borrow it from a friend or

a family member okay so the first thing

is i'm using a basic tripod here this is

a me photo

road trip it just has a nice ball head

and it's collapsible

it's about 100 bucks for the camera i'm

using a stock

canon 60d which is a 18 megapixel

dslr made about 10 years ago i bought

this one on ebay for about 300

the lens is the nicest piece of gear

this is a canon 200 millimeter

f 2.8 l lens i bought it directly from

canon's refurbished site for six hundred

dollars

and i find it's a really good lens for

astrophotography

but don't feel you need to use what i'm

using if you already have a telephoto

lens a tripod and a camera

then you are set the last two pieces of

equipment are optional

but highly recommended the first one is

some kind of intervalometer

if your camera has an internal

intervalometer

you can use that or maybe an app or

something

and then maybe you don't need this but

for us with older cameras like this 60d

this is a really nice 30 dollar purchase

you just plug it in it's simple to use

and it's how we're gonna take pictures

of the night sky without introducing

vibration you can see it shaking around

by touching the camera

the other accessory i really like is a

bodenav mask which is a focusing aid

i 3d printed mine so that it's a perfect

match for this lens

and i'll put the link in the description

for the video where i talk about 3d

printing them but you could also just

buy one they go for something like 20 to

40 dollars

and that's it for equipment five things

tripod camera

lens baud enough mask intervalometer the

fourth thing to take a photo like this

is proper technique and processing

and this is going to be the hardest of

the four but i'm really going to try to

keep it as simple as possible in this

video

i'm going to break the capture technique

down to a few things

first choosing the right shutter speed

and iso

then when we get on the field achieving

perfect focus

manually with the lens then finding

andromeda galaxy and taking hundreds of

photos of it so that we can stack them

together and

average out the noise and finally taking

calibration frames called bias darks and

flats these each address a different

kind of

noise or problem with your camera or

lens and by using them properly we can

make our final photo look even better

and then after we've captured our photos

we need to

process them to create our final picture

this is sometimes called data reduction

meaning we take

hundreds and hundreds of photos and we

reduce them all down into one

final photo and processing in this video

will be done with two programs a free

windows program called deep sky stacker

and then adobe photoshop however in the

next few days i'll release various part

twos to this video that will show you

how to process using

other programs including completely free

open source programs like serial and

that work on any operating system

including mac and linux

okay that was the overview now let's

jump into the step by step

step one we need to choose an iso and

shutter speed for a gear

choosing an iso is all about the

camera's sensor and we try to balance

readout noise

and dynamic range typically higher isos

offer

lower readout noise but at the cost of

decreased dynamic range

but let's take all the guesswork out of

this we're going to use bill class

excellent website photons to photos look

over here

there's a series of interactive charts

and we're looking for the fourth chart

down called input referred read noise

chart okay and the first step in using

this interactive graph

is picking your camera from the list

over here on

the right i'm sorry if it doesn't have

your camera

but it does have a lot of cameras so

chances are it does have your camera i'm

going to choose the canon eos 60d

because that's the camera i'm using

and then you want to pick an iso based

on

this chart where it starts leveling off

in terms of readout noise readout noise

is something that's present in every

shot that you take

so it's not something like photon noise

that you can

average out and use things like kappa

sigma clipping to get rid of

and so we want to pick an iso that has

an appropriately low read noise

usually somewhere below 2 electrons

is good so on my canon

60d that happens around iso 1600

but we're even closer when we get to iso

3200 so that's what i'm going to shoot

at tonight is iso 3200

if i was on a tracking mount i would

probably

pick 800 or 1600 because then i can do

longer shots and then read noise

isn't as big an issue um but

since we're doing many many one-second

exposures read noise is a big issue

and i'm gonna pick iso 3200 where

read noise is uh pretty low

now you might ask why not just go all

the way to iso 6400

and the reason is is because there's not

much difference between 3200 and 6400

and if there's not much difference you

don't want to go to the higher iso

because it's limiting the dynamic range

of the camera

basically every iso setting that you

pick that's higher

you're limiting the amount of

information that can be

recorded in a single shot and so

i would always err on the side of

getting more dynamic range

when two readout noises are pretty

similar

and this leads me into iso lists or iso

invariant cameras

if you do happen to have one of these

your chart would look more

like this basically just a very

slow sloping line rather than this very

dramatic

uh stair step line that i have on my

canon

so this is the nikon d5600 and you can

see

this is what an iso invariant camera

would look like the

the readout noise barely changes across

the iso

range um so for this camera i would

probably be comfortable

anywhere from iso 200 and i probably

would never shoot at iso 3200

because there's just really no point

but for my canon 60d it does make sense

so that's what i'm going to go with

tonight

hopefully this made sense basically

again just the key

is where you see this chart start

leveling out for your camera pick the

lowest iso

where it starts leveling out so for

this camera that arguably could be

either iso 1600 or 3200

but i'm going to go with 3200 tonight

choosing a shutter speed is about

getting the longest exposure possible to

let in the most amount of light

before the stars get misshapen and turn

into lines due to the earth's rotation

the best resource i've found to figure

out shutter speed is frederick michod's

npf rule

and he has a handy calculator the link

will be in the description

and this calculator allows you to

calculate ideal shutter speed

and it is in french but if you're using

google chrome you can

just click up here in the address bar

and translate it to your language of

choice

and we basically just go through this

calculator and fill in the details so

if you uh don't see

your camera in the list here you want to

leave it on

other and enter data manually and then

just look up

for your camera the size of a photo site

or a pixel

and the number of pixels and if you just

type in

your camera and pixel size

one of the first results should be this

digicam database

and this almost always includes

pixel pitch or pixel size same thing so

for this camera it's 4.29 microns and

then if you scroll down a little bit

it also includes the the image

resolution

so you would just enter these things in

here

or if your camera is in the list you can

just select from the list and it will

enter them

for you then we move on to your lens or

what it calls the objective

and this is the focal length here so

for me it was 200 and i

shot it 2.8

aperture okay

if you're not sure about these don't

worry too much about it but

you can look them up in a planetarium

program like stellarium or

a planetarium app on your phone like sky

map quite easily

so

andromeda is going to be to the

northeast

and at a latitude of about

42 degrees and the target

height above the horizon in degrees was

going to be about

35.

okay and then we'll click calculate the

exposure time

and it tells us down here that we can

shoot for

1.1 second uh well actually more like

one second

and even if we could do 1.1 second i

would round down anyways because

uh i can't set up my camera to shoot 1.1

second it has to be in increments of one

second so one second two seconds so

forth

so anyways this tells us the correct um

shutter speed for 200 millimeter lens

shooting to the northeast with

this particular sensor in the canon 60d

is one second exposures

okay so first step we figured out the

iso and shutter speed step two

we have to find a dark sky and again

what i recommend is light

pollutionmap.info to get an idea of

where dark skies may be near you

if you can find others who do

astrophotography in your area through

astronomy clubs or maybe social media

they may know some good spots in your

area and then you can go together and

it's always safer and more fun to have

an astrophotography buddy to shoot with

all right step three

we've arrived at the dark site we have a

full battery we're shooting in raw with

the iso and shutter speed we figured out

from step one

let's now point our camera at a bright

star and focus it

the first step is to make sure you are

in manual focus

you're going to set the focus to

infinity if your lens has a scale

and get a good grip on the focusing ring

on your lens

next you're going to turn on live view

and hopefully you should see the star

you're pointed at

if not moving the focusing ring back and

forth

should help you see it if you don't have

a bad enough mass the trick to focus

is just getting a bright star as small

as possible

and you're going to move this focusing

ring

back and forth and just try to find that

point where the star is smallest

to really see the star though we need to

zoom in so find the zoom button on your

camera and zoom in as far as you can in

live view

now when you're really in focus what

should happen is all of a sudden you'll

see

other smaller stars just pop into view

on screen

and then as soon as you lose that best

focus they'll disappear again

this is a bit hard to see in video but

i'm going to show it to you with jupiter

because the jupiter is really bright

and what happens when we get jupiter

into focus is all of a sudden we'll see

a little line of moons pop

in now if you do have a bod knob mask

just go ahead and pop that onto the

front of the lens here

and all you need to do now is get that

central spike that we see on the bright

star

right in the center of that x pattern

and you do need a bright star to see

this pattern and if you still don't see

it even with a bright star just take a

one to two second

exposure and look in playback mode and

the pattern should appear

once you have that all lined up with the

x and then the central spike

you know that you have perfect focus and

we can move on

all right step four now we just have to

find andromeda

and to do this i suggest using a free

planetarium app on your smartphone

i'm using sky map here on my android

phone

i'm just going to move it around with

the camera until m31 is centered

m31 is just the the name for andromeda

and the messier catalog

and what you see here in in sky map or

any other planetarium app is that

there's two bright stars in pegasus that

form a line with the galaxy so i'm just

going to try to find those in my live

view here

here they are i'm going to keep going up

a bit until the

upper of the two bright stars is at the

bottom of my screen

i'll then go ahead and take a picture

and you see

right there that little fuzzy blob

that's the andromeda galaxy

now the stacking program will take care

of alignment based on the star patterns

in the picture

so we don't have to be super precise but

about every 50 shots or so we want to

re-center andromeda in the shot

and i'd always recommend every time you

reframe take a test shot

and then check framing and focus if both

look good

then we can go ahead and take the next

set of 50. and we just want to repeat

this as many times as possible

the more photos we take the less noise

we have to deal with in the final photo

okay step five we've taken our photos of

andromeda but we can't quite pack up yet

our andromeda photos are what we call

our light frames meaning

the actual photos that we took of the

night sky to get really ideal results

though

we now want to take calibration frames

so in addition to the light frames we

also want these calibration frames and

we're going to start with

dark frames for dark frames we want to

leave all the settings alone

same iso same shutter speed all we have

to do is cover the lens with the lens

cap so that no light is hitting the

sensor

now i'm sure many of you are wondering

can we just take these later on after we

go home

the answer is no these need to be taken

at the same temperature

as the lights so you really do need to

take them here on the field

but with such short exposures these are

really quick to take we'll just we just

want

50 so we'll just leave the same setting

on the intervalometer we're going to do

one second each

so we're just going to cover the lens

hit start on the intervalometer

and that's it next up is bias frames

you can technically take these anytime

but we might as well take them now

all we want to do is change the shutter

speed i'm going to change it from one

second

down to as fast as the shutter can go on

your camera for my camera here that's 1

8 000 of a second

and let's take 75 bias frames okay and

last up is

flat frames and it's important to take

these very

soon before or after you take your light

frames because we want everything to be

the same in terms of focus and any dust

particles on the lens or the sensor

so i wouldn't even recommend turning

your camera off if you can help it

we just want to take these as soon as

possible to take these we take the lens

cap back off

and we point the lens straight up and

i'm going to rubber band a clean white

t-shirt to the lens hood

you want it to be taut with no wrinkles

then we place a white screen on top and

this can be any

pure white screen if you have an ipad

you can set to white or a laptop you can

set to white that will work

if you want to buy something just for

this purpose what i'd recommend is an

led

tracing panel these go for about 30

bucks and they're powered with a usb

cable

whatever you have that produces a white

light just put that on top

and now we're going to move the shutter

speed up and down

with the dial here until this exposure

meter at the bottom of the screen is

telling us we're properly exposed

to check that we just push the shutter

down halfway and i'll tell you right

here

so for my particular setup here it's

showing proper middle exposure at 1

40th of a second so i'm just going to

set my intervalometer to take 50

and hit start okay that's it we've

captured a thousand light frames

50 dark frames with the same settings as

the lights just with the lens cap on

75 bias frames which are lens cap on but

shortest shutter speed the camera can do

and 50 flat frames which are middle

exposure with a white t-shirt and a

white screen on top of the lens

now we can pack up and go processor

photos on the computer

okay i've now transferred all my files

from the camera onto the computer and

organized them into these four folders

bias frames dark frames

flats and lights

and now what i'm going to do is i'm

going to open up the free program

deep sky stacker which you can download

from the web

and then i'm just going to follow along

here on the left hand side

starting with open picture files

and i'm going to start by opening up all

of my

lights so i'm just going to go into the

lights folder

click on one and then press ctrl a to

select all of them

and click open okay they come in right

here you can see that we have a long

list of

light frames but for some reason it says

light frame zero

so that's just because by default it

doesn't check them so we're just gonna

click

check all over here on the left hand

side and now we can see we have 992

light frames

i did take a thousand but i'm just

looking through them a little bit on the

camera i noticed at least eight that had

clouds or other problems like focus

problems

so i've already deleted those and we

have 992

and then i'm just going to add the

calibration files that we took so

starting with dark files

we'll go into my darks folder here press

ctrl

a click open

so we've added 50 darks then i'm going

to click on flat files

go into my flats folder again press

control

a and open 46 flats

and then finally click on offset bias

files

go into my biases folder press ctrl a to

select

all and click open and we brought in 74

bias files

so now that we have everything loaded we

can

go down to this command this that's

highlighted in red right here that says

register checked pictures i'm just going

to click

into advanced and click compute the

number of detected stars

it tells me 75 stars were detected

and usually what i do is i'm gonna lower

the threshold a little bit

until that number gets up over a hundred

so at fourteen percent

it got up to 116 stars that sounds good

and you might have to keep lowering your

threshold you could lower it all the way

down to

5 or something but just you want at

least probably 100 stars

to match on okay i'm going to leave

automatic detection of hot pixels turned

on

i'm going to check stack after

registering and say select the best

95 of pictures and stack them

if you wanted to look through the

quality of your different pictures

before stacking them you could uncheck

that and then

it will give every picture a quality

score and you can

do some extra work based on that but i'm

going to leave that part out in this

video just because this is going to be

i'm just trying to keep it as simple as

possible i would recommend

clicking on recommended settings and

just looking through this and make sure

that there's nothing that stands out

that you have to

do you want to make sure that all the

settings are

set and then you'll see that all these

things

show in green based on what's

recommended

and that's it then we're going to go

ahead and

click ok and it will go through this

whole process

of registering the pictures meaning

looking at the star patterns

and matching them up so that all of the

pictures

are lined up in terms of the stars and

then once it's done that it can stack

them meaning

averaging them and by averaging them

it pays attention to where the signal is

in the picture so the stars and the

andromeda galaxy but the the noise will

be

more random from picture to picture and

so

by applying what's called kappa sigma

clipping

we throw out that random noise because

it's so inconsistent

um so that's how stacking works

one other thing is because there's not

much room left on my laptop here

i am using a temp folder on an external

drive

so if you do need to do that you just

click into stacking parameters here and

then you can pick

an external drive or usb thumb drive to

hold your temporary files folder because

uh for this picture it's going to be

quite

large so i'm going to click ok

and tells me we're stacking a thousand

pictures at one second each so that's

equivalent to about

16 minutes total exposure we can see

everything was taken at iso 3200

and it tells me that this process will

temporarily use

109 or close to 110 gigabytes on the d

drive and i only have 169 gigabytes free

so

getting close there um but i'd have just

enough

free that that should work so let's go

ahead and click ok and let it do its

thing here

this is going to take a long time so i'm

just going to probably leave it

overnight and we'll check up

on it in the morning this estimated

remaining time

that's just for the current process so

don't feel like it's going to be done in

four minutes it's really going to take

hours and hours to do all this since

we're dealing with so many

frames so this three minutes

is just to stack the bias frames

then it goes through a bunch of

different things because it creates

masters for each calibration file

it calibrates all the lights it lights

it registers all the lights which takes

a really long time

and it stacks all the lights which again

takes a lot of time so

i'm just going to leave this and then

when it's all done we'll pick up

there okay it's finished it actually

took it almost 22 hours to

complete this whole stacking process

calibration registration and stacking

this is what you want to see when it's

done meaning it's going to be in a

linear state meaning

the picture should be mostly black you

might see a few little white

spots these are bright star cores but

you don't really want to see

anything too bright at this point if

everything went correctly it should look

pretty black like this

and it does do an autosave file so

in your lights folder you should find an

autosave.tiff

i will warn you that that's a 32-bit

file so

if you are using older versions of

photoshop

or that don't have 32-bit support

you may not want to use that file

otherwise it's fine to use but

just to be safe i'm going to show you

how to save off a 16-bit tiff file

under the processing section right here

you just go to save picture to file

make sure that it's set as save as type

tiff image 16 bits per channel

we'll give it a name i'm just going to

call it m31

dash dss

and under options you want this option

to be selected embed adjustments in the

saved image but do not apply them

compression i leave set to none and so

i'm just going to save this to my

desktop click save

here it is and so this is what i'm going

to bring into my next step

into the post processing program i've

switched over to my mac

because that's where i have photoshop

installed and i've just opened up

the tiff file directly from deep sky

stackers

stacking process so you can see this is

what it looks like it looks just like it

did

when we were done with the deep sky

stacker steps over here

on my layers panel i have the background

layer

i'm going to go ahead and immediately

duplicate that layer

just by right clicking on it and

choosing duplicate layer

and i'll call the new duplicated layer

first

stretch okay and then the first thing

we're gonna do

is uh open up the histograms window

and i'm gonna switch it from compact

view which was the default

to all channels view to show

the three different colors red green and

blue

okay and now we can start stretching

so to do that i'm going to go to image

adjustments

levels or i could press ctrl l if i'm on

windows or command

l on mac and i'm going to take this

mid tone slider the one in the middle

here and just bring that

quite far over something like that

and i'm going to do that same thing

again

so i'm just going to take that mid-tone

slider and again

bring it pretty far over to the left

so i'm moving it from the middle over to

the left

okay and now we can see some separation

from the left hand side so everything

was over here compacted in the shadows

area

but by stretching we're bringing the

information out here in

closer to the mid-tones and we can start

seeing some stuff come out here

now i can see that immediately we have

an issue where

the red channel is getting a little bit

out in front of the green and the blue

and also the blue looks the most

anemic of the three well the red channel

looks a little bit fatter

so another thing we're going to try to

do is as we're stretching

get these not only to be lined up

somewhat but also the same

width so there's just as much

information in the red channel

as there is in the green and the blue

channels and we can do that

with the levels command so i'm just

going to bring it back up again

and so far we've been working on the

whole image at once by having it in

channel rgb but we can always break it

down

into the individual channels by

stretching just the blue just the green

or just the red

so i'm going to start by stretching the

blue

basically what i'm trying to do is

make it about the same width and about

at the same

spot as

the red channel and i'm going to do that

with by using both the midtone slider

and the shadow slider so i'm going to

start with

bringing the midtone slider over to the

left and then i'm going to take the

shadow slider

and bring that over a little bit to the

right

and it's helpful to look up at this view

too because i can see in that view that

the blue

is coming out a little bit beyond where

the red is

so i'm just going to take that shadow

slider and move it a little bit

like that until they're better lined up

then i'm going to do the same thing with

the green channel

but it doesn't need quite as dramatic

a stretch but i'm just going to

do something like that all right

so we're going to hit ok and you can see

the image is starting to come out here

let's go ahead and do some more

stretching i'm just going to bring up

levels again

i'm going to take the midtone slider and

move it

over to the left i'm going to take

the shadow slider and move that to the

right a little bit

okay and at this point i'm going to

close that for a second you can always

bring it back open by just doing that

one thing to note here is that we have

a sort of reddish look along

the corners but there's really not much

information out here that i'm interested

in i'm

going to crop in anyways i'm planning to

so

let's go ahead and just crop in now

and i'm just going to crop in

closer in on the galaxy something

like that all right next what i want to

do

is i want to add a little bit of

saturation

and also work on the color balance a

little bit more

but i'm going to use adjustment layers

to do this because they're not as

destructive to the image meaning we

don't have to go back in history to get

back to a previous state we can actually

just

turn the adjustment layers off and on or

adjust them on the fly

so the first one that i'm going to use

is this hue slash saturation adjustment

layer

and i'm just going to um push

the saturation up

let's try 40 and we can always back

off later but this just sort of gives me

an idea of what the color looks like

now and the color

looks too green especially in the galaxy

so what we're going to do is we'll apply

a

color balance adjustment layer and we're

going to remove

some of that green cast by just taking

the green magenta slider

okay uh with that done all right this is

looking good but um i want to do some

other things to it including a second

stretch of the data so

i'm going to make a new copy or a new

layer

from what is visible here and so to do

that on a mac you do command

option shift e as in the e key and on

windows it's ctrl option shift e

okay and then you can see here in my

layers panel there's a new layer one

i'm going to call that second stretch

and i'm just going to again open up my

levels command and just try

to give this a little bit

more of a boost

something like that and you can see that

what we're seeing now is that

these outer edges of the galaxy

um that before were a little bit hidden

in the darkness of the sky

and at this point i'm instead of using

levels because we were sort of running

out of room to do much more with the

levels i'm going to open up a curves

adjustment

so that's command m on mac or control m

on windows

and this just lets me do a little bit

more of a subtle thing than the levels

when the levels you basically just have

control over

a midtones point a shadows point and a

highlights point

in curves you can make the points

wherever you

want so um

so i could make a point there

and a point there just to try to add

a bit of contrast to the galaxy

and what i'm seeing now is that the the

background is looking

far too red so i'm also going to open up

a um the red channel in curves and just

take this

shadow point and just move it over a

little bit

so that that red wash of the background

goes away

okay so hopefully you can see that we've

made some progress here this was the

first stretch

and then with one more round of levels

and a bit of work in curves here is the

second stretch

so one thing you may notice is that this

is actually

the um orientation of andromeda galaxy

with

north being up so if we're thinking of

the the upper plane of this image being

towards the north star

this is how andromeda would look but

most people

rotate their images 180 because it just

uh

is the way that we've grown accustomed

to looking at andromeda there is real no

there's no real up in space but um

let's go ahead and just do that because

it feels more natural at this point so

i'm just going to rotate

180 by going to the image menu and

choosing image rotation

180. okay there we go

and at this point i'm liking how

andromeda is looking other than maybe

being still a little bit too green

one thing we could do to control that a

little bit is open up that

curves again and just open up the green

channel and just take a point over here

in the highlights

and bring it down just a little bit

so i really like how the galaxy is

starting to come out

in this second stretch but our colors

are probably getting a little bit

wonky except for in the galaxy i think

actually they look pretty good

um so we might have to do a little bit

of work with let's do a curves

adjustment layer

and let's just play around with this red

channel a little bit

and i'm just going to play around with

each

channel separately and what i'm doing

is i'm just basically resetting

black points putting different points

close to the black point

until i get something that to my eye

looks more natural so you can see i

think both the blue and the magenta

were too and the red i guess were too

high

in the the blacks here so

by adding a little bit of green and

taking down the blue and the red

we've corrected that white balance issue

but the stretch on the galaxy

is preserved because if we were just to

look

at what we had before second stretch you

can see it looks a little green and

there's not much that's popping out here

along the outer edges

the second stretch got us those the

outer part of the galaxy

but then we just needed to fix the color

a little bit okay

and uh this is

sort of a nice faithful representation

of of the data that we

got i could stop right now and call this

a day it looks

really good considering this is

untracked one second exposures

but i want to bring it a little bit

further along

and to do that we want to separate out

the stars

and the dso because if we don't what

will happen

if we keep just trying to push the dso

without separating out the stars you can

see what happens

is that i just added a huge saturation

bump

is we can get the the

galaxy looking sort of cool but then the

stars become

way too gross looking um i'll turn that

back off

see how it's just like well at one it

brings out all problems in the

background it makes the stars way too

colorful for my taste um

and so it's much easier to keep pushing

this image

if we can separate the stars and the

background and the dso

and then work on them separately and

then recombine them

so to do that let's use that command

option

shift e command again or control option

shift e

if you're on windows and then i'm just

going to save

this uh stars as a 16-bit tiff file so

i'm going to do

file save as i want to use tiff

i'm going to turn off layers so it just

makes a flattened

one layer image and i'll call this

stars and save it to the desktop

then what i'm going to do is i'm going

to google

star net plus plus this is a standalone

program that's

useful for removing stars from

astrophotography and i'm going to

download it from this

sourceforge page and if you go to files

up here at the top

and then go into version 1.1 they have a

nice

zip file for each main type of operating

system so since i'm on a mac i'm going

to download the mac version

okay once that's downloaded i'm just

going to move the entire

starnet macos folder onto my desktop

here

and open it up and then i'm just going

to open up

this run rgb starnet dot

sh file with a

text editor i'm just going to change

these two file names

be the first one being the input file so

we called that stars.tiff

and then i'm going to change the

output file to m31starlist.tiff

this number is the stride

and typically i use a lower stride when

i'm at a lower focal length and a higher

stride when i'm at a higher focal length

um it starts at 128 but you can go down

to 16.

i'm going to change it to 64 for this

image

and typically the the lower the stride

number

the longer the process takes so if you

wanted to see what will happen

if you run it quicker you can leave it

on the default 128.

okay then i just have to move this

stars.tiff into the same directory

okay with that shell file edited like

this and the stars.tiff file in the same

directory we now just have to

run this file a terminal

command so i'm just going to open up

terminal

and we have to get into this folder so

the command for that is cd for change

directory

space and then i'm just going to drag

this folder over and hit

enter and then we just want to run

this command or this sorry this shell

script which

calls on the actual program so to run it

all i have to do is just drag it over

and hit enter and it starts running it

gives us a little information about

the file it tells us how many different

tiles it's going to break it the image

up into to analyze

that's what the stride number is so

the slower the stride number the more

tiles it will break the image up into

and then the longer it'll take

and then it gives us a percentage

finished so this will take some time

probably 20-30 minutes on my laptop with

an image this

size okay starnet finished up pretty

quick we now have the mm31 starless file

i'm going to go ahead and right click on

that and open it up in photoshop

there we go there are a few little

artifacts holes but we'll deal with

those in processing but what you should

be able to see is without all the stars

getting in the way we can really see a

lot of cool details in m31 including all

of the

dust lanes the spiral dust lanes here

first thing i'm going to do

is just apply a curves adjustment

just to sort of see what we have a

little bit here

okay it looks pretty good but there's

still

a bit of a green cast here in the middle

so let's just go back into that curves

and just tamp down

the green just a little bit up here on

the high end

but try to keep it steady here in the

mid tones

see if that helped at all yeah that

looks pretty good

okay now i'm going to apply some

saturation

go back into curves and just make that

curves adjustment even more dramatic

okay and at this point what i want to do

is i want to create a mask so that i can

desaturate and darken the sky background

and work on the galaxy

separately from this sort of messed up

sky back here

so the way i'm going to do that is i'm

going to

make a new from visible copy so

command option shift e on mac or ctrl

option

shifty on windows and i'm going to go to

image adjustments

useless saturation and just remove all

saturation

from that layer

i'm just going to grab my pen tool here

and i'm just going to

create a sort of rough shape

around the galaxy here

like that and then i'm just going to

click on selection and say i want to

feather it

by 15 pixels

okay so now we have a selection around

the galaxy

and i actually want to

select everything else other than the

galaxy so i'm going to do

select inverse and then i'm going to

just

add a curves adjustment layer

and darken this up quite a bit

but then i want to go ahead and blur

that uh

mask that i just made on the curves

layer because right now it's very sharp

so i'm just going to do filter blur

gaussian blur

and do something like

80 pixels so now it looks like this

and i also want to apply that to

this little satellite galaxy so i'm just

going to grab a brush

and brush that on like that with black

i'm just going to go ahead and merge

these two

just right click after selecting both of

them and do

merge layers

and i'm just going to apply a

very small levels adjustment

just to make that a little bit brighter

and just to be sure i'm going to go

ahead and

paint in black on the corners so that we

don't have any

weird stuff coming through basically i

just want

the galaxy to be brighter

and i think it should actually be even a

little brighter still so i'm going to do

command m

just make it a bit brighter here

okay that looks good so all we were

doing was creating a mask we can just

call it

mask here

and i'm going to go ahead and select all

and copy that and then

let's make some new hue saturation

layers and we can turn the mask off

and then apply it to those layers so i'm

going to hold down the

option key or alt key on windows and

click on that

and paste in the new mask that we made

and i'll do it on this one as well

on this one i'm going to invert it so

i'm just going to press command

i and on this inverted one i'm going to

also make it a bit

darker

okay so now we've done all this work

with masks we're going to actually now

apply what we've done

so on this one since white selects

this is going to be a saturation

boost so i'll just rename that one

saturation boost

and on this one this is going to be a

desaturate layer

so i want to desaturate the background

and saturate

the galaxy well actually it looks

already pretty saturated so i'm not sure

if i'm going to use that but let's start

by desaturating the background so i'm

just going to take this

saturation slider move it to the left

take the lightness slider

and move that to the left as well

okay now that we have this actually

neutral black background

i can see the issues with color balance

in the galaxy a lot more clearly and so

i'm going to create a new

curves layer and apply

the mask to it

there we go

and i'm just going to do this by eye

just looking at the

at the galaxy here so it has a little

bit

too much red

in the outer arms

so you see the difference there but

that red is actually important to the

core

because when i take it away the core is

getting too

cyan the green ish color

so what i'm going to do is i'm going to

duplicate that layer

just right click and

duplicate layer and call this one

core

and i'm going to basically

do the opposite with

the red

to get a sort of uh nice

warm core how andromeda should look

so

we've now just done the opposite on that

one though but that

basically returned us to where we were

with the outer

arms looking too red so i'm going to

go on to this mask

just with a soft brush have that not

apply

to anything but the core area here

okay so sort of subtle but

here is where we

were before and

here is

taking some of the red out of the arms

and then here's returning some of that

red

to the core area

now now that i have this core mask let

me try to take out even a little bit

more green

out of that core and for that i'm going

to use

a color balance so let me just

go ahead and apply this layer mask to

the color balance

adjustment layer just by holding down

alt or option on mac

and dragging it so option drag or alt

drag on windows is going to

allow you to copy that layer mask

onto this layer and then it says do you

want to replace the layer mask i say yes

and now with the color balance i'm just

going to

add yellow

and magenta and red

to that core area so here's before

there's after so again a fairly subtle

difference but i think it really does

make the picture sing a little bit more

uh without it

i just think it doesn't look as as

balanced this

color balance looks better to me and i'm

just doing it

mostly by eye here and at this point

we're almost done with the starless

rendition of the galaxy but i just want

to make it a little bit brighter

so i'm just going to add another curves

layer here

and just brighten it up a little bit

okay i think this is ready to go

so this is our starless andromeda

now we want to add the stars back in so

to do that we're going to go back here

to

our stars layer which is now looking

very magenta compared to this so let me

try to just fix that a little bit first

sorry i know a lot of there's been a lot

of

color adjustment steps here just reset

that just a little bit

there we go okay i'm going to

select that copy it

command c on mac or ctrl c on windows

and i'm going to paste this on top

okay it's now pasted on top and i'm

going to change

the blend mode from normal to

screen okay and it already looks pretty

good but the only thing we have to do

now is just

maybe reset the black point and decide

on a final crop

so i'm going to open up curves again a

curves adjustment layer

and just take this black point and

reset it here

i'm just seeing if there's anything else

i could do with the color balance

a little bit i'm just going to do one

more color balance

try here on the core now that i have the

stars in

so i'm just going to do that same trick

of

dragging the layer mask for my core

back onto there and i'm just going to

add

a bit of yellow

and a bit of red and i'm just going to

extend

the core out here just a tad

okay so here's before there's

after hopefully you can see that it just

needed an yet another just

final little adjustment where we shifted

some of the green and blues out of the

core

to make that really sing

now that i'm looking at it up close now

though i think we could maybe boost the

saturation again

but let's do that actually in adobe

camera

raw because i'm also want to do a little

bit of

noise reduction so i also noticed that

it's a little bit

off-center so i'm just going to center

this up and to

apply an adobe camera raw correction to

this um

if you are in an older version of

photoshop you can just save it off as a

tiff file and then open it back up into

photoshop with the adobe camera raw set

as the format

if you're on a newer version like i am

here you can just make

a new from visible so i'm just going to

do command option shift e

that would be control option shift e on

windows

and i'll call this acr for adobe camera

raw

and then i go to the filter menu and

just choose camera raw filter

and from here we have all these sliders

uh if you've used lightroom before you

probably are familiar with a lot of

these

and some of them are pretty interesting

what they can do

to a

astrophoto so for instance

if you want to get sort of rd you can

take

this dehaze filter and

move it over to the left and it adds

this cool like

glow uh to the galaxy and you know if

you just

want to just maybe apply a little bit of

that

you could just you know add a little bit

so there's definitely a lot of

artistic things you can do with the

camera raw filters

i'm going to add a little bit of

vibrance and saturation

to the picture and i'm going to add

some color noise reduction

some luminance noise reduction and some

sharpening

and when applying these filters i like

to look at the

picture at different scales to sort of

see what they're doing

you can temporarily

turn them off and on with this little

eyeball

and honestly they've just gotten better

and better with each version of

photoshop like

to me that's that's really only

improving

the picture not taking away all right um

so i'm happy i've done a few little more

nitpicky filter things for

color again and i'm just going to save

this

i'm going to save it as a photoshop

document

just call it m31.psd

save it to the desktop and then i'll do

export save for web legacy

and do a jpeg

okay here's our final result again this

was about

980 stacked one second exposures from a

canon 60d 200 millimeter lens

we processed it with deep sky stacker in

photoshop and here's what we got

so it sort of shows that even with just

a 15 minute integration

if you know what you're doing with the

processing you can get a really nice

photo even without a star tracker i hope

that

this tutorial on being a time traveler

and seeing back

two and a half million years in time has

been useful to you

and if so you can support me by

subscribing to this channel

i also have a patreon which starts at

just one dollar a month

and until next time this has been nico

carver from nebulaphotos.com

clear skies

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