Photo & Video > Outdoor > Astro Landscape Photography > Post Processing: Star Trails Stacking

Post Processing: Star Trails Stacking

 

Astro Landscape Photography

 

Lesson Info

Post Processing: Star Trails Stacking

Here we have the images that we shot with the intention of combining them in post processing to make a single image with longer Star Trails. You may remember that we had eight eight minute exposures, all shot at F4 ISO 1600. And we also have two frames here that were intended to be used for light painting and we did those before we started the second sequence. This one was just 90 seconds, and I wasn't concerned with the background exposure, just wanted to get some light painting in. So add this little flashlight in the burning bush, and then the flashlight out of camera off to the right on the rocks. Got this deep shadow here, but I think that's gonna be taken care of by the ambient exposure over here. This one was an eight minute exposure as well as the rest of them for the stack. But unfortunately there's about a minute of time in between this exposure and the next one. Which means there will be significant gaps in the Star Trails. As a result, we're not going to use the sky from th...

is one, which is too bad 'cause it would make our Star Trails that much longer. So you'll also notice there is a significant amount of ambient illumination on these shots. The orange glow is from the candles that we were using for the Creative Live team, so they could basically film what I was doing. And the rest of the globe, both in the sky and the increasing brightness on these exposures is the moon rising over the horizon during the hour plus that we were doing this stack in sequence. What we're gonna do here is make some basic Lightroom adjustments to these images, sync them together and then we'll combine them, using stacking techniques. We're gonna two different stacking techniques. One is a Photoshop script called Dr. Brown's Stack-A-Matic. And that is my preferred method because the end result is a layered Photoshop file that allows you to adjust individual layers and make corrections for errors in individual frames. The other method is called StarStaX, and that's a quick down and dirty way of stacking images that it's much quicker, but the end result is a flattened JPEG. The one advantage to StarStaX, in addition to being faster is that it does have a gap filling mode, which is sometimes an issue in the way the raw files are read. There sometimes appear very small gaps in between the Star Trails. Anyway, let's get started, alright I'm gonna take this the last image in the stack. Go to the develop module and we've got a bit more exposure than I want to here, so I'm just gonna bring it down. Oh three quarters of a stop, that looks pretty good there. This orange a little bit strong, so I'm gonna go to the HSL tab. I'm going to use the targeted adjustment tool. I'm gonna reduce the saturation. Mouse over this orange area and you can see that orange slider is going down. I'm also going to go to the luminance tab here and also take the targeted adjustment tool, and reduce the luminance of also the orange. And you can see the red came down just a little bit. There we go, it goes. Here we are straight out of camera, and here we are with those basic adjustments. Alright, think I'm going to increase the contrast just a little bit here. I typically like to do that/ And with the recent versions of Lightroom, I find the contrast slider to be quite useful. In earlier versions, say Lightroom 4 or earlier, I probably would have gone to the tone curve and adjustment my contrast there, but the global slider works very nicely now. I'm gonna be careful using clarity at this point, in terms of combining images and stacking them. I'm gonna wait till later to use any clarity, let see. Basically don't need a whole lot of adjustments here but I do wanna go down to lens corrections in particular, make sure that I check profile corrections and chromatic aberration. Also let's go into the detail tab, see what noise we have in this image. It was a really hot night. I think it's about 90 degrees when we were filming, and the background luminesce noise is not too bad, but there are a number of colored hot pixels that you can see here. And unfortunately, Lightroom noise reduction doesn't do all that well with hot pixels. We can move the color slider all the way over and see if that helps a bit, and it does reduce the color in some of those hot pixels, but it doesn't make them go away. I'm always hesitant to use a whole lot of luminesce noise reduction especially on an image like this where it doesn't have a whole lot to be corrected for the luminesce. Let me just push it all the way over and show you the effect here. Once it renders, you'll see we're gonna have a tremendous loss of detail here. The images is, there it goes. It just gets real mushy, not good at all. I'll give it just a couple of points but not very much, and hopefully combining the images together using the stacking process will take care of some of these hot pixels. Sometimes it does, sometimes it doesn't. Okay, looking at this again, I still want a little bit more contrast so I'm just gonna pump it up, just a little bit more, and I'm also gonna open up now that I've made the darks darker. I'm gonna open up the shadows a little bit. Matter of fact, I'm gonna push it all the way over, and that looks pretty good to me. So I've made a few basic panel adjustments. I have made detailed adjustments. I've correct the noise. The color noise all the way up. Luminesce noise just a little bit. I should probably compensate for the luminesce noise adjustment by increasing the sharpening a little bit. Generally you wanna do that with the image at 1:1. Let's see, I'm also gonna hold down the option key, or the alt key on the PC, and here's this masking slider here. So what you can see when you first activate it. Everything that's white is being sharpened, but we don't really wanna sharpen the noise. So you move the slider over, and so only what's white is being sharpened. And basically, we don't wanna sharpen the noise. So that's alright, let's see. Turn the panel off and see what difference it makes. Yeah, you can see that color noise in those hot pixels really jump out without it. Okay, no bad. Alright, so I will go to the grid monitor now. I'm gonna select all of these images, and make sure that this one is highlighted. Go back to develop, choose sync, make sure that they are all checked. I'm gonna synchronize these images now. Go back to the grid module, and you can see those change is taking effect on the rest of the images. And basically, you should notice that orange saturation fading. Yeah, there we go. It's just taking a while. Images get a little bit darker. Okay, now I will do some individual adjustments on the two light painting frames. First on this one, you can see there's a bit of an oops here. And what I'm gonna do is take the smart removal tool and just clone that out. You would see where Lightroom chooses to clone from, and in typical fashion, somewhere inappropriate. So let's grab our spot round and move it down here. Let's see, what's this? Okay, press the H key to hide our spots, and I'm okay with that. It looks pretty good. Let's go back here again. I just notice myself in there. A little bits of myself that happen to show up while I was adding this light to the burning bush here. So I guess, I will choose smart removal tool, and I don't have to worry about this too much because we've got these other images to work with in the stacking process. That will cover up any of these little areas. Here we go. Just taking a lot of render there. Okay, alright now as I mentioned before, there are gaps in between these Star Trails and the ones in the stack images that we're gonna use. We're not gonna use this part of the sky, so what I'm gonna do is take a break in, and I'm going to reduce the exposure, highlights, shadows, whites and blacks. I'm gonna reduce them to the maximum and I'm gonna create a fairly hard edged gradient. Basically illuminating that whole part of the image 'cause I know we don't wanna use any of that. Alright, that's about that. That's about, let's go back. Take a look at this one. What adjustments do we wanna make around here? Well, I know we wanna do the same thing. We're obviously not gonna use this sky in this image, but I do probably wanna use some of this light panning. So I'm gonna make sure my gradient ends here. Move it down for us, a little bit, okay, alright. I'm gonna press the O key to show that mask. I'm gonna press the H key to hide the gradient. I'm going to choose brush. I'm gonna press the option key or alt on the PC, and I'm gonna brush away this area because well, I just might wanna use that in my stack. Here we go, and it doesn't matter how precise I am with this because we have a lot of different layers that we're working with. So there we go, we've illuminated the sky. This is really bright down here, isn't it? I'm just gonna darken here. I don't think we have to worry about this too much from the other images, but I still probably want to open up the shadows. We've got them up already from the synchronizing on the other ones. So let's see, can we increase the closure a little bit on this particular frame. Yeah, a bit. Not too much, bring the highlights down. So that's neutral exposure, and we brought the highlights down about 30 points. This is too bright. I could use either a local adjustment brush or a gradient. I might as well use the brush. Double click on the word effect to reset the tool. I'm gonna reduce the exposure and the highlights. I typically use highlight shadows white sand blacks in combination with exposure and often contrast. Let's see what it looks like here. I will activate the auto mask, increase the flow, decrease the feather and brush it on here. Now the green is just the mask, press the O key to make that go away. And well, it's less bright but I wanna crank up the contrast. Let's see, alright. Here we go, that's showing the area where that brush is applied. And somehow it looks a little bit off color compare to these other rocks. I'm also going to add some tint here. Now let's see, it looks a little bit greenish. So I'm gonna go towards the magenta. I'll go heavily, just so you can see the effect. I would say that's way too much. But maybe just a few points away from the green and towards the yellow, a few points a way from the blue. And let's just bring down the saturation just a touch. Okay, so there we go. How about this one here? Come on, let's render. Looks a little bit hot, so I might do a local brush on there are well. There we go. Yep, I knew that was gonna be hot when I was shooting it. Alright, so let's do a new brush, reset, highlights down, auto mask off, a bigger feature, a smaller brush and there we go. That's maybe a little bit too much. Let's bring it back. Bring it back just a bit. Okay, I think this image is ready to go. Alright so we have synchronized our eight stacked images and we've made some local adjustments to our light painting images. This one, the page is not reading. There we go, that's better. Alright, so at this point. We have our images with the processing and Lightroom. Unfortunately Stack-A-Matic is not available directly from Lightroom. So what we're gonna do is minimize Lightroom. Go over into Adobe Bridge. Okay, so here we go. Here are the eight Star Trails images plus the two light painting images. And at the command date, I select all of them. Go up to the tools menu, and choose Dr. Brown's services, Stack-A-Matic. That's going to give us a couple of options. Number one, we want the default to create layers instead of a smart object. And number two, we always want the default set lend mood to lighten. That's going to make whatever is lighter in each successive image appear and come through making the Star Trails grow. Only use the auto align feature if you are shooting on a windy night, or if you think you may have bumped your tripod. Otherwise, it just takes a lot of extra time to process the images. So we're gonna just use these default settings. Click on okay. So some time has passed, and Stack-A-Matic has done its work. And here you can see is the layered file. And we've got 10 different layers, each one with a blending mood set to lighten. I'll just go ahead and turn them off, one at a time so you can see the effect of each one of those layers. Notice the Star Trails getting shorter. Here we go, so single image. And there's that last bit of the dramatic overkill lighting. So now basically, we have to decide what we're going to use here. We would like just the subtle bit of lighting or do we want something little bit more dramatic? And if we wanna use this one, perhaps maybe we'll just reduce the opacity a bit. And have it not quite so strong, but that also mutes out the burning bush. Maybe we'll turn this one back on again. Here we go, that looks pretty darn good. Okay, I wanna look at this image at 100%. And you can see there still are some hot pixels and looks like we've got a couple of satellites or maybe a shooting star or so in here. Oh wow, that's interesting. Looks like it, curved over two different exposures. There's one and there's the other. Interesting huh? So we've discovered that there are what appeared to be satellites or possible meteorite, but probably satellites in two of our images. And let's just say for whatever reason we wanted to remove them. So we've got the empty layer mask here that's added by Stack-A-Matic. And I'm going to click on the mask, choose the brush, make sure it's set to black. We've got a nice small brush that looks about right. So I will just brush over that satellite, and make it go away. And let's see what else. That's about it for that one. The other one, I think is on this frame. Yeah, okay, so now I click on the mask, and we'll just brush over it. And here we go on this one. Alright, so we've got a tiny little gap in here because this portion of the Star Trails happen to be on that layer. But it's a small price to pay, and it's not gonna show up in the larger image. Alright, so here we go. Here is our image and I'm pretty pleased with this. So now, we're gonna save it, and we'll bring that back into our Lightroom catalog and maybe make a few tweaks on there. Now because we did not initiate Stack-A-Matic from Lightroom, only because we can't. The image will not be directly imported into our Lightroom catalog. We'll have to bring that it manually. Oh yeah, that's one other thing, just take a look here. This is this little blurry bit here. That's the core of the Milky Way. That dense part of the galaxy. Okay, so let's bring it back into Lightroom, and import. Let's navigate to our folder. Go into pictures folder, and maybe with stack. And there is our image, and it's already in the folder where we want it so we're just going to add it. There it is. The still is a layered PSD, and if we open it up in Photoshop, we'll have access to all the different layers. Well first thing I probably wanna do is a gradient with some clarity for the stars, not too much about 20. Lay that on there. Increase the contrast on that gradient a little bit. Now that just makes the Star Trails stand out. So there it is without the adjustments and there it is with the gradients. Okay, let's close that. Take a look in the basic tab. At this point, that orange is still a little bit intense because of the accumulative effect of all those different files. I'm going to reduce the vagrants just a little bit here. And one thing I know I wanna do this image is a post graph vignette. So it just pulls that whole image together. So I'm gonna move the amount slider to the left. Midpoint slider a little bit to the left and then I'm gonna feather the image, and move the feather off to the right. So that's with and without. With and without, and there we go. I think we have a completed stacking image using Dr. Brown's Stack-A-Matic. In the next little segment, we'll do the same thing with StarStaX. In this last section, we're gonna take a look at StarStaX which is freeware, available for both Mac and PC at StarStaX.net, that's S-T-A-X. It's pretty simple to use and it's also very quick. Advantages over Stack-A-Matic are the speed, and also that it has gap filling mode for little spaces in between Star Trails that sometimes happen due to the way the files are rendered. Contrary to popular belief, the gaps in between Star Trails are not due to the one second gap in between exposures, but the way the files are rendered. It also has this comet mode which will render the Star Trails as tapered trails looking like comets. I find it a little gimmicky but a lot of people like it. Anyways, very simple to use. We've got our images here, the eight images for trails. One image for light painting, and I've selected them all. I'm just gonna drag them over here into the StarStaX interface and they load. We're just gonna go with the default settings right here. And under the edit menu, start processing command P on a Mac. It's very quick, it only takes about 10 or 15 seconds for these nine images. 13 seconds, okay there it is. Here we can look at it at 1:1 and see. I don't really see much in the way of gaps. They're just barely precitable, but certainly nothing to be concerned about. We still have the same basically same level of noise and the hot pixels in there. Let's save this image. And we'll bring it into Lightroom and take a look at it with the Stack-A-Matic side by side. Alright, let's bring it into Lightroom. Right on the desktop. There it is, and we're gonna put it right there. Perfect, okay so here's our Stack-A-Matic image. Here is our StarStaX image. Go to the compare module and the end result is fairly similar. Star Trail rendering is pretty similar. There's the satellites from the StarStaX image. Doesn't have quite the level of punch in the StarStaX image but I guess that's not really a fair comparison because we did go back and make some adjustments on the Stack-A-Matic version. Let's go and sync these two. That's the easiest way to do a direct comparison. Now apply the same host stacking adjustments to the StarStaX and the Stack-A-Matic images. Back to the compare mode, and for all intents and purposes they look pretty similar, but remember what we've got with the Stack-A-Matic file is a layered Photoshop document that can be adjusted even at this point on the individual layer basis. We do have a little bit more highlight detail in the Stack-A-Matic version. The Star Trails rendering is pretty comparable. Neither one did a tremendous job at removing the hot pixel noise. And again, the reason that we had that hot pixel noise is it was about 90 degrees or so at the time we were shooting this. And one thing I'm noticing here is the shadow remains in the StarStaX image, and is not over here in the Stack-A-Matic image. Anyway, they both have their advantages and disadvantages. There are also other applications you can use. The Stack-A-Matic basically, you can also achieve the same thing by selecting your files in Lightroom open as layers in Photoshop, and then set the blending mode to lighten to each one of those. And then of course, you'll have to add the empty layer mass on top of each layer if you wanna make more adjustments. So there it is, stacking for longer Star Trails than you would have in a single image.

Class Description


The solar system and the magic within it can be seen with more than just a telescope. Capturing the milky way and the movement of the solar systems around us can make for engaging and out of this world photography. In this class you’ll learn:

  • What equipment to use and setting your composition in the field 
  • How to find your focus and exposure in the dark 
  • How to capture star trails and the best opportunities based on the lunar calendar 
  • How to capture the Milky Way and create striking panoramas of the night sky.  
Lance Keimig is the author of Night Photography- Finding Your Way In The Dark and leads photo tours around the world.