 I just built this star tracker for about $30. It's a very simple mechanism. Instead of using a motorized gear to track the stars like in a commercial star tracker, this tracker makes me the motor, and I manually track the sky by turning this threaded bolt and this counteracts the Earth's rotation. Stick around and I'll explain how it works, show you how to build one, and then we will do a real-world test of it by shooting several two-minute exposures of the Milky Way and the Ro Wufiuki Cloud Complex, which is beautiful, with a basic DSLR and a 24mm lens. Hello there, my name is Nico Carver and my YouTube channel, Nebula Photos, is all about helping people learn astrophotography. I'm especially interested in how to approach astrophotography on a budget. Of course, many aspects of astrophotography become easier if you just throw money at them, and it's easy to go down a gear buying rabbit hole I've been guilty of it myself, but I also enjoy getting the most out of budget gear and budget techniques, which is what I'm going to be showing you tonight with this. I do have a Patreon to support this channel, and if you join the Patreon, you can also join my Discord server, which is a great place to ask questions and talk to others in the Nebula Photos community, including me. I'm going to say up front here, I'm not super skilled in DIY stuff, but when I read about this Star Tracker that's basically just two boards connected by a hinge with a ballhead on top and then a threaded bolt that you turn to track, I thought, well, this sounds simple enough that even I should be able to make one. I did and it works. The inventor of this Star Tracker is George Haig, who released the idea for free and described how to make it in this April 1975 issue of Sky and Telescope Magazine. It's sometimes called a Scotch mount because George Haig is Scottish, and probably the most common name for it, though, is a barn door tracker. It's been a popular DIY project for amateur astronomers ever since he published this in 1975, and there have been many different versions of the design improvements to it, maybe, but I'm going to make the original Haig design both to keep the cost low and because I'm fascinated by the simplicity of it. Before we jump into making one, let me just very quickly explain how this kind of tracker works. And it's pretty easy in terms of the math, so this isn't going to take too long. The reason the stars move from our vantage point is, of course, because the Earth is rotating around its axis, and the Earth moves 360 degrees or one full rotation every 24 hours. For the astrophotographer, what this means is that if you just point your camera at the night sky and leave the shutter open for a long time, the stars will trail, meaning turn from little points to arched lines that we call star trails. This of course also blurs out any deep sky object like a nebula or galaxy. But one way to get around this, which I've described in several other videos now, is just to take very short exposures and then stacking many hundreds or thousands of these short exposures together with stacking software. The name for this that's sort of catching on is untracked astrophotography. And untracked astro works well, but it just has some definite limitations. The main one being that you have to take hundreds and hundreds of photos, and so that can wear out your mechanical shutter in the DSLR. And then it also just takes a long time to, you know, transfer all the files and stack them all together on your computer. And another limitation is that it works really well for bright deep sky objects like Orion and Andromeda, but not so well for dim ones. So to solve this, we usually turn to star trackers, which just move at a constant rate that's opposite the Earth's rotation in the opposite direction. And that lets us take much longer exposures with the camera, with pinpoint stars. So as I said earlier, Earth is rotating 360 degrees every 24 hours. We can divide that down to 15 degrees per hour or 0.25 degrees per minute. So if we look at these two boards, what we really need to do is move one away from the other at a rate of 0.25 degrees per minute. And that will keep up with the stars. Now, a very common piece of hardware that you can buy is a quarter inch 20 bolt, meaning it's quarter inch in diameter, and it has a thread spacing of 20 threads per inch. And so that's what we're going to use to drive our mount. Because we can drive that at one revolution per minute. It'll travel one inch every 20 minutes or 0.05 inches per one minute. So we know now, okay, we have to move 0.05 inches per minute, and we want the boards to move apart from each other at 0.25 degrees. So all we need now is to solve this equation. And if you remember some trigonometry, you might already know what's coming here. What we do is we use a simple formula. And what we need is the hypodenduse. And the hypodenduse is going to equal the opposite side of the angle. So we know that's 0.05. We know the angle is 0.25. So what we can do is divide by sine times the angle. So 0.05 divided by sine times 0.25, and we get 11.4 inches or 290 millimeters for those metric folks. And so we want the hole for the bolt to be 290 millimeters away from the hinge. And then if we track at one rotation per minute, we're going to get perfect stars. And yes, for this to work, we also need to be polar aligned. And so that's the hard part keeping this build on the cheap. And so what I did is I'm just using a metal drinking straw on here, taped right by the hinge to site polaris. But really, this is the first thing that I want to improve in my next revision of this mount as the straw to site polaris is really a bit of a pain to use. It's not that accurate. And it won't work for the southern hemisphere. So I'm on the lookout for a used finder scope. I mean, a used polar scope would be even better. But something, a laser, I don't know. But let me know in the comments if you have any kinds of ideas for an accurate way to polar align this kind of mount, a DIY mount as cheaply as possible. OK, anyways, now that we know how it works, let's go through the steps of building it. And I made a PDF guide you can download from the link in the description for building it. I'm going to go through the steps fairly quickly. So the guide will be a helpful reference if you want to look at that while you're building one yourself. Step one, measure and cut two pieces of 1 by 6 lumber to 12 and 11 and 16 inches long. That's 322 millimeters for the metric folks. If you don't have a saw, Home Depot or other kind of home improvement hardware stores might cut the lumber for you in the store. Step two, put your hinges, or hinges if you're using two, along the edges of the boards to mark out where the holes are going to go and then drill some small holes to attach the hinges. And then you're going to screw on the hinge with some small wood screws. I'll just note here, I was able to find a six inch long hinge and I'll put a link in the description of one online that I found. If you can't find that though, two smaller hinges, like two three inch hinges, would work just as well. It should now look like this with two boards connected by the hinge. Step three, now you want to measure out a spot on the bottom board exactly 11.42 inches or 290 millimeters from the hinge and make it centered in terms of top to bottom on the board. And mark this and then drill a quarter inch hole there. You're then going to glue and hammer in a quarter inch t-nut into the top of the bottom board. And when you glue it or epoxy it, be careful not to get any of the glue into the threads of the t-nut. It's just to secure the t-nut to the board a little bit better than you could by just hammering it. Step four, repeat step three, except this time put the t-nut in the exact middle of your bottom board so that that would be six and five sixteenths of an inch or 161 millimeters. This is where you will attach the tracker to your tripod. Step five, I've lost the sunlight so I'm indoors now. This is how your tracker should look and you can go ahead and screw in the long quarter inch 20 carriage bolt with the round head into the t-nut that is 290 millimeters away from the hinge. This is going to be your drive bolt for the tracker and you can test it out if you want. Step six, print out the pattern I'm providing to make your clock wheel. You can just print it out on regular printer paper and glue it onto a CD. But if you happen to have every CD labels like I did laying around, you can use those, makes it even easier. Step seven, we're now going to secure the clock wheel and handle, which is, I'm just using a sort of little metal brace here I found, to the bottom of the drive bolt. I'd recommend using some nuts, washers, and epoxy and then tighten it all up with some pliers so that it's all secured very well to the bottom of the bolt and very permanent. Once you have all of that done, you should be able to easily turn the bolt up and down with the handle like this and the clock wheel will rotate around. Now go ahead and decide where to attach your ball head to the top board and drill a hole so you can attach it with a shorter quarter inch 20 bolt. I put my ball head in the center lengthwise but towards the top widthwise and putting it towards the top of what will be the north end of the board because I'm going to be mostly using my tracker for Milky Way, which will always be to the south here. So I was thinking for balance with lenses that the weight would be more distributed equally this way if the lens is coming out towards the south. I'm not sure if this really makes any difference but that was the thought behind it. Step nine, measure the center point of your boards at the end of it where the clock wheel is and drill out two little holes for the screw eyes and you can just screw those in by hand and then you can attach a rubber band around these to give a little tension to the system and turn the screw eyes this way so you can look down and see how your clock wheel is pointed right through the center of those. And step 10, attach your polar alignment device and align it with the hinge of the tracker. As I said earlier, the drinking straw works okay but for very wide angle lenses like I'm using I'm going to be doing 24 millimeters but to use this at 50 or 70 millimeters I think I'd need to find a better polar alignment device. And that's it. Let's go test it. Okay it's 3 20 a.m. I'm at a Bortle 4 site. This will be my first Milky Way of the season. I'm really excited. I'm ready to actually try this thing out and the first step is we need to polar align it. And I'm just going to try to site Polaris with this metal drinking straw. Just try to center it in the straw. Polaris of course is the the last star in the little handle of the little dipper. And this is just going to be a good enough polar alignment. Not a great polar alignment but since Polaris is actually about a half a degree off from the pole but hopefully for a wide angle lens like this 24 millimeter this will work well enough. So here we go. All right the second step now that polar aligned is we have to find our target by moving the camera around on the ball head until we're pointing at it. So I want to be pointing at the Roe Oofyuk area which is pretty easy to find because there's a bright visible reddish star called Ontaris which is right in the middle and it's part of again the easy-to-spot Scorpius constellation. So here we go. I'm just going to go find it. The third step now is I want to focus on the stars using the live view. I'll just zoom in to 10 times and try to make the stars as small as possible on the screen. The fourth step is I'm going to put the camera into bulb mode and just connect this simple bulb timer or shutter release so I can take two minute long exposures. This has a little lock so I'll basically just start an exposure lock it and then at the end of two minutes unlock it. So now we're all ready to start tracking. Let's see how it goes. Okay my first few tests were not successful. I was still getting sort of trailed stars. I found through a lot of trial and error though that with this camera and lens I'm using here which again are the Rebel T7 or 1500D and the Rokinon 24 millimeter lens at 2.8 that I need to move the clock wheel or the the bolt at a rate of every 2.5 seconds. I thought maybe I could get away with every five seconds but I'm getting trails still. I'm getting much rounder stars by moving it 15 degrees every two and a half seconds rather than 30 degrees every five seconds. So it's not too bad it's just a little bit tough on my neck to keep looking down at it but I can adjust the tripod height to sort of fix that. I'm just using the stopwatch on my phone to watch the seconds go by and I've just done some short tests so far. But let's go ahead and take a full two minute exposure now that I think I have it working and we'll see what we get. Wow will you look at that? I'm amazed at how good this looks. This is just a kind of single two minute exposure with this barn door tracker. Let me zoom in on it so you can see what I'm seeing here. Just really good detail. Stars are nice and sharp and round. I think this is gonna be a keeper. I'm gonna try to take as many as I can before sunrise here so I'm gonna get right back into it. So I've taken ten two minute exposures. They're all looking good but I'm getting close to the bottom of the bolt so I'm gonna go ahead and rewind it by turning it clockwise now this way. Okay I'm done rewinding it. I'm not gonna have to re-point the camera on my object because by rewinding it I probably threw off the pointing a little bit and then I'll take ten more two minute exposures and probably by then the sun will be rising and I'll have to stop. So we'll have 20 two minute exposures for 40 minutes total. Well it's the next day I've gone ahead and processed what I shot last night and I got to say I'm pretty impressed by this barn door tracker. I wasn't so sure if a manual tracker was gonna be able to keep up with a modern DSLR with small pixels but as long as you rotate the bolt frequently enough to avoid trailing I found it works really well. That took a little trial and error. Of course the big advantage of using this tracker over just shooting on a fixed tripod is to get 40 minutes total time on my target like I did last night. I only had to shoot 20 photos at two minutes each. If I was shooting without a tracker to get to 40 minutes I would have had to do 600 photos at four seconds each. So taking hundreds of photos will wear out your cameras shutter faster and take a lot longer to stack on your computer. Of course there's some cons to this tracker too. The manual nature of it made it a bit uncomfortable on my neck to be looking down at it for 40 minutes just slowly moving that wheel and I suppose some people would also find it pretty boring to just manually track that long. So keep those things in mind. What's next for this project? Well I want to buy a used finder device like I mentioned with maybe a crosshair ip so I can better polar align and that will allow me to try longer focal lengths because I've only really tried it seriously at 24 millimeters. I did try a little bit longer focal lengths but I wasn't getting good results. I think it was because of polar alignment error. So once I've done like a version two of this I also want to test it against some of the cheaper commercial options like this Omegan LX2 wind-up tracker and the Move Shoot Move which is a little bit motorized tracker but it's very small. And so you can look forward to a part two eventually where I will show you my improvements and try it against these options. You know $30 tracker versus a little bit more expensive ones. Well the only thing left now is the image reveal. So let's start with the single unprocessed two minute exposure. Here it is cropped in a bit to fill the screen and we can zoom in on some stars here just to show you that they are indeed round. Okay and here is after and all I did in the processing was really you know stack with I think I did 12 darks. I didn't have time to do flats or bias so it was just 20 20 lights and 12 darks matched temperature darks. And I just stacked those in DeepSky Stacker brought this into Photoshop and did my usual sort of playing around with curves and saturation and stuff. I also just want to mention here again at the end that I have a Patreon and another perk of my Patreon is I now have an exclusive video just for people who support me on Patreon and that the topic of that video is choosing different types of DeepSky objects and what kind of gear filters and sky conditions you might need for different types like if you want to shoot a star cluster do you need a filter do you need a dark sky that kind of thing. If you want to shoot a constellation what's the best focal length for that. So I go through some different types of DeepSky objects. So if you're interested check out my Patreon it starts at just one dollar a month. Until next time this has been Niko Carver from NebulaFotos.com Clear Skies!