 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 $1 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 lightpollutionmap.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 use to take this photo, I spent under $1,000. 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. OK, so the first thing is I'm using a basic tripod here. This is a Mi Photo road trip. It just has a nice ball head and it's collapsible. It's about $100. 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 F2.8L lens. I bought it directly from Canon's refurbished site for $600. 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 purchase. You just plug it in. It's simple to use. And that's how we're going to take pictures in the night sky without introducing vibration. You can see it shaking around by touching the camera. The other accessory I really like is a Bodinov 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. And that's it for equipment. Five things, tripod, camera, lens, Bodinov mask, intervalometer. The fourth thing to take a photo like this is proper technique in 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 in ISO. Then when we get on the field, achieving perfect focus manually with the lens. Then finding a drama to 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 year. 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 gonna use Bill Claff's 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 gonna 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 two 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 gonna 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. 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 pretty low. Now you might ask, why not just go all the way to ISO 6400? And the reason is because there's not much difference between 3200 and 6400. And if there's not much difference, you don't wanna 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 read out 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 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 read out noise barely changes across the ISO range. 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 6D, it does make sense. So that's what I'm gonna 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 gonna 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 Frederic Michaud'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 don't see your camera in the list here, you wanna 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 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 at 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 Skymap 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 gonna 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. Well, actually more like one second and even if we could do 1.1 second, I would round down anyways because 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 shutter speed for 200 millimeter lens shooting to the northeast with this particular sensor in the Canon 6D 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 pollution map.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 gonna 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 gonna 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 bottom of mass, the trick to focus is just getting a bright star as small as possible and you're gonna 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, it'll disappear again. This is a bit hard to see in video but I'm gonna 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 bottom of 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 SkyMap here on my Android phone. I'm just gonna move it around with the camera until M31 is centered. M31 is just the name for Andromeda in the Messier catalog. And what you see here in SkyMap 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 gonna try to find those in my live view here. Here they are. I'm gonna 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 recenter 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. We just wanna 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 wanna take calibration frames. So in addition to the light frames, we also want these calibration frames and we're gonna start with dark frames. For dark frames, we wanna leave all the settings alone, same ISO, same shutter speed. All we have to do is cover the lens with a lens cap so that no light is hitting the sensor. Now I'm sure many of you are wondering, can't 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 in 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 and we're gonna do one second each. So we're just gonna 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 wanna do is change the shutter speed. I'm gonna change it from one second down to as fast as the shutter can go on your camera. For my camera here, that's one eight thousands 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 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 wanna 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 gonna 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 wanna 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. So whatever you have that produces a white light just put that on top. And now we're gonna 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 gonna set my interval on her 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 process our photos on the computer. Okay, I've now transferred all my files from the camera onto the computer and organize them into these four folders bias frames, dark frames, flats and lights. And now what I'm gonna do is I'm gonna 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 gonna start by opening up all of my lights. So I'm just gonna go into the lights folder, click on one and then press control 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 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 gonna add the calibration files that we took. So starting with dark files. We'll go into my darks folder here, press control A, click open. So we've added 50 darks. Then I'm gonna click on flat files, go into my flats folder again, press control A and open. 46 flats. And then finally click on offset slash bias files. Go into my biases folder, press control 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 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 100. So at 14% 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 gonna 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 gonna leave that part out in this video just because this is gonna 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 wanna make sure that all of the settings are set and then you'll see that all of these things show in green based on what's recommended. And that's it. Then we're gonna go ahead and click okay 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 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. 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 for this picture, it's going to be quite large. So I'm going to click okay. And tells me we're just stacking 1,000 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, but I have just enough free that that should work. So let's go ahead and click okay 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 I 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 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 that 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-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 Stacker's 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 going to do is open up the histograms window and I'm going to 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 control 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. And 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 mid-tone slider and the shadow slider. So I'm going to start with bringing the mid-tone 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 okay. 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 mid-tone 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 huge slash saturation adjustment layer. And I'm just going to 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, with that done. All right, this is looking good, but 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 control 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 that before were a little bit hidden in the darkness of the sky. And at this point, 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 mid tones point, a shadows point and a highlights point in curves, you can make the points wherever you want. So I can 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 background is looking far too red. So I'm also going to open up 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 orientation of Andromeda Galaxy with North being up. So if we're thinking of 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 is the way that we've grown accustomed to looking at Andromeda. There's no real up in space, but let's go ahead and just do that because it feels more natural at this point. So I'm just gonna 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. 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 gonna 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 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 a 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 the outer part of the galaxy, but then we just needed to fix the color a little bit. Okay, and this is sort of a nice faithful representation 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 wanna bring it a little bit further along. And to do that, we wanna 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 galaxy looking sort of cool, but then the stars become way too gross looking. I'll turn that back off. See how it's just like, well, one, it brings out all problems in the background. It makes the stars way too colorful for my taste. 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 gonna save this stars as a 16 bit TIFF file. So I'm gonna do File, Save As, I wanna use TIFF. I'm gonna 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 gonna do is I'm going to Google StarNet++. This is a standalone program that's useful for removing stars from astrophotography. And I'm gonna download it from this source forage 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 RunRGBStarNet.sh file with a text editor. I'm just gonna change these two file names. The first one being the input file. So we called that stars.tiff. And then I'm gonna change the output file to m31starless.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. It starts at 128, but you can go down to 16. I'm gonna change it to 64 for this image. And typically 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 from a terminal command. So I'm just gonna 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 gonna drag this folder over and hit enter. And then we just wanna 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 gonna break it the image up into to analyze. That's what the stride number is. So the lower 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 MO31 starless file. I'm gonna 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 gonna 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 gonna apply some saturation. I'm gonna go back into curves and just make that curves adjustment even more dramatic. Okay, and at this point what I wanna do is I wanna 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 gonna do that is I'm going to make a new from visible copy. So command option shift E on Mac or control option shift E on Windows and I'm gonna go to image adjustments, use less saturation and just remove all saturation from that layer. I'm just gonna 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 wanna 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 gonna 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 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 gonna grab a brush and brush that on like that with black. I'm just gonna go ahead and merge these two, just right click after selecting both of them and do merge layers. And I'm just gonna 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 gonna 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 gonna go ahead and select all and copy that. And then let's make some new hue slash saturation layers and we can turn the mask off and then apply it to those layers. So I'm gonna 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 gonna 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 gonna 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 wanna desaturate the background and saturate the galaxy. Well, it actually looks already pretty saturated. So I'm not sure if I'm gonna use that, but let's start by desaturating the background. So I'm just gonna 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 gonna do this by eye, just looking 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-y green-ish color. So what I'm gonna do is I'm gonna duplicate that layer, just right-click and duplicate layer. I'm called this one core. And I'm going to basically do the opposite with the red to get a sort of 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 gonna go onto 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 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 gonna 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 wanna 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. Without it, I just think it doesn't look 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 wanna 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 wanna add the stars back in. So to do that, we're gonna 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, it's been a lot of color adjustment steps here. Let me just reset that just a little bit. There we go. Okay, I'm going to select that, copy it, command C on Mac or control C on Windows. And I'm gonna 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 gonna open up curves again, a curves adjustment layer, and just take this black point and reset it here. Just seeing if there's anything else I could do with the color balance a little bit. I'm just gonna do one more color balance try here on the core now that I have the stars in. So I'm just gonna do that same trick of dragging the layer mask for my core back onto there. And I'm just gonna add a bit of yellow and a bit of red. And I'm just gonna extend the core out here, just a tad. Okay, so here's before, here's after. Hopefully you can see that it just needed 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 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. 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 gonna 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. If you've used Lightroom before, you've probably are familiar with a lot of these and some of them are pretty interesting what they can do to a Astro Photo. So for instance, if you want to get sort of arty, you can take this Dehaze filter and move it over to the left and it adds this cool like glow to the galaxy. And if you just want to just maybe apply a little bit of that, you could just add a little bit. So there's definitely a lot of artistic things you can do with the Camera Raw filters. I'm gonna add a little bit of vibrance and saturation to the picture. And I'm gonna 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 really only improving the picture not taking away. All right, 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 gonna 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 6D 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 $1 a month. And till next time, this has been Nico Carver from NebulaFotos.com. Clear skies.