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 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 MeFoto
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 200mm 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
Bahtinov 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 Bahtinov 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
gimp 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 Bahtinov 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 gimp 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!
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 Bahtinov 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 gimp 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!