...shoot stars, planets and other nebulae, with a camera that is.
No Arduino, no stepper motors, no gears, just a simple motor turning a threaded rod, this barn door tracker rotates your camera at the exact same rate as the rotation of our planet, a requirement for taking long exposure photos.

The concept isnt new, its been around since the 70's, back in the days of 35mm film, my version updates it to motor drive and adds a corrective cam to remove the inherent error in the original version.

Briefly, the common ways of doing this are the single hinge 2 boards with a straight threaded rod, the single hinge 2 boards with a curved threaded rod and the doubled hinged 3 boards version.
All versions can be motorised, but the 2nd version with the curved rod has the motor driving a nut through gearing and the curved rod is held stationary.

An example here of Dennis Harper's curved rod tracker.https://sites.google.com/site/distar97/
Gary Seronik's fine curved rod tracker here  http://www.garyseronik.com/?q=node/52
Finally Dave Trott who invented the double-arm tracker. http://davetrott.com/inventions/double-arm-barn-door-drive/

Step 1: Parts and Tools

Mostly hand tools were used with the exception of a mitre saw to get the ends for the hinge mount nice and square. I also used a drill press for drilling the holes for the sliding motor rails so that they are parallel to each other, as well as the hole for the drive rod to ensure it was nicely perpendicular.

  • A decent hinge with very little play, I went with a solid brass 63mm one seeing as the plank width was 69mm.
  • The main part of the tracker, 500mm pine 22m X 69mm.
  • The camera mount, approx 300mm of 22mm X 44mm meranti (a hard wood, well harder than pine anyway)
  • A brass 1/4" 20 modified machine screw for mounting the camera.
  • M8 nut and bolt for mounting the cam mount to the main body.
  • M6 rod ~ 90mm with wingnuts and washers for the tilt axis in the camera mount.
  • M6 nut and bolt 50mm long for attaching the tracker to the tripod.
  • 16 wood screws, 6 for the hinge and 10 for reinforcements in the camera mount.
  • A 70mm X 50mm section of plastic cutting board for the corrective cam.
  • A 230V AC synchronous 1 rpm motor.
  • 2 x steel rods to fit the motor mounts, 4mm in this case.
  • M6x1mm threaded rod 135mm long out of which I get a usable length of 90mm, @ 1mm pitch that translates to 90min
  • M6 coupling nut to connect the motor shaft to the drive rod with split pins to fit.
  • M6 Tee nut for the bottom board's drive rod.
  • An existing sturdy mount like a camera tripod or a diy contraption to suit, bear in mind some tripods have a plastic pan tilt head assembly and wobble a fair amount.
Something to note with the drive rod, M6 is a nice middle size, M5 would have a smaller board length of 185mm hinge to drive rod distance and possibly very flimsy, M8 would be more robust but would need a hinge to drive rod distance of 285mm which might become very bulky.

Lastly, a camera is also a requirement, preferably a DSLR with remote in order to use the "bulb" setting for long exposures. On my Nikon D70S I use an infrared remote because the camera wont allow bulb setting with the timer, it just overrides with 1/5 sec exposure.
That said, it might be theoretically possible to use a Canon PowerShot (point n shoot range) and load it with the CHDK software to utilise the intervalometer scripts.
<p>I have built a few trackers over the last few years, using a slightly different design and a curved rod for greater tracking accuracy. I like this article, the camera mount in particular is very ingenious. You can get a lot of parts for a tracker from this guy - google bencooper.karoo barn door tracker. He uses the design first published by Gary Seronik.</p>
I think I love you... :p
<p>I really love this instructable! I've almost finished mine, will post pics when it's ready. The links to the cam are not working at the moment. Is there anyone who can help me out with the correction cam? Thanks!</p>
<p>Thanks for the heads up, those links are now dead. Google didnt help, other than to find a site that had copied my ible and those links didnt work either.</p><p>Here's the jpg which I saved to an external h/d, fortunately. :)</p>
<p>I'm glad that I found this image but the translating it is a bit off....I've figured out by the rest of the comments I'm supposed to print this so the arrows are 65mm long, but I can't figure out the placement exactly.....can anyone help?</p>
<p>Placement of what?</p><p>The subsequent plastic cutout is placed at the initial contact point of the threaded rod.</p>
<p>Yep that was it...thanks...I kind of figured but just wanted some confirmation</p>
You are my hero! Thanks!
<p>Thanks so much for these instructions! I have nearly collected all the pieces needed but after testing the 1 rpm motor it seems to be taking about 65 sec to complete the rotation instead of 60sec. Will this affect the outcome too much? Or should I go down the arduino path (on which I have never trod) and try to change that? </p><p>Your advice is greatly appreciated.</p>
It will be problematic because the calcs assume 1 rotation and not 1.05 etc.<br>You will need new calculations regarding thread size and board length.<br>Try a speed check with it running off an inverter, if its better then that would be a convenient way to go.
<p>Hi,</p><p>I am almost done making this, but need to know the exact position where I need to place the camera mount, in this case I am using a 360deg Ball head instead of a ALT-AZ mount.</p><p>Thanks</p>
<p>There is no &quot;exact&quot; position, the entire length travels at the same time/speed.</p><p>Closer to the hinge but keeping the center of gravity above the tripod mount is a good pratical solution.</p>
<p>if I had to use another engine with 12v 3rpm I should change something about your project right?</p>
Yep, you would need to redo all the claculations involving rpm and threads per inch etc.<br>http://davetrott.com/inventions/double-arm-barn-door-drive/
<p>Hi,</p><p>Thank you for sharing the design of the star tracker.</p><p>Could you please tell me where you got the M6 tee nut and the M6 coupling nut?</p><p>Thanks!</p>
Hardware store http://www.brightsonline.co.za/
<p>&quot;He also stresses that the jpg must be printed to the scale according to <br>the drive rod thread pitch which in my case was 65mm square.&quot;</p><p>I am little confused about the corrective cam print size. I am using 1mm pitch thread rod, could you please clarify...</p><p>thanks in advance.</p>
<p>If you open up that jpg and just plain print it you might get a scale error, (you might have<em> print to fit page</em> as default) so he has included 2 red arrows, vertical and horizontal so that you can measure the final printout to make sure it is 65mm both vertically and horizontally, ie 65mm square.</p><p>Makes more sense if you've looked at the pic.</p>
<p>I tried Irfan View like you mentioned in another commet, that seems to have worked... thanks again.</p>
<p>I am trying to source the motor for this setup and found this </p><p><a href="http://www.audiomate.co.uk/proddetail.php?prod=Black-4W-1-Rpm-CW-Replacement-Motor" rel="nofollow">http://www.audiomate.co.uk/proddetail.php?prod=Bla...</a></p><p>Could you please tell me if this motor is what you have used?</p>
That's the one yes, same front pic too.<br>http://www.fort777.co.za/index.php?main_page=product_info&amp;cPath=269_270_423_1093&amp;products_id=6939<br><br>Sometimes when I switch it on it goes CCW and I just flick the power to make it go clockwise again.
<p>Could you please tell me how much the motor weighs? </p>
<p>116 grams</p>
<p>Thanks a ton!</p><p>Regards</p>
<p>awesome, thank you Sir for a quick response..... and for sharing this in such detail... </p>
<p>Hello,</p><p>This is so awesomely simple. I'm a noob in Astronomy, DoItYourSelfery and even this forum, but Im going to give it a go! THANKS for this! However, I'd like to or have to use US Standard nuts, bolts and rods. So which calculations must I use or attributes about the rod must I know? The part under calculations:</p><p>Nice to know: <br></p><ul> <br><li>M8 x 1.25 ...<li>M5 x 0.8...</ul><p>the 1.25 and the .8, what are those numbers? It seems if I knew those numbers of an M5 equivilant in US Standard I can find everything else. </p><p>Thanks again!</p><p>Will</p>
The M8 is 8mm dia and the 1.25 is the thread pitch, ie 1.25 mm per full thread<br>Alas you cant convert because then the other dependables wont match up.<br>I've seen imperial thread of 1/4&quot; 20 on some of the other builds.<br>this site is using imperial threads in the build http://www.philharrington.net/scotch.htm
Hi. <br>Thank you for the answer. <br>I got quite a bit done. <br>Few questions remain if you please. <br>https://www.instructables.com/files/deriv/FD1/9XIY/HPFZR1CA/FD19XIYHPFZR1CA.THUMB.jpg <br>A green- Is this length important, in example, must the camera sensor be directly over the hinge? <br>B yellow- I think this relates to question 1, my fault. <br>C blue- The length of upper part? <br>D purple- Where on the arm do you put the alt-azi upper part? Near end, directly over the part where you will mount it on the tripod I guess? <br>E white- Length of the lower part. <br>F black-How do you know how many degrees to turn this? <br> <br>I think F is maybe the only really important thing, the rest don't really matter?
A &amp; B not important, i just located them in the middle so I could easily access the thumbscrew underneath. <br>C can be as short as practically convenient. <br>D can be anywhere bearing in mind the closer you put it to the screw rod the more weight will be at that point=more strain on the motor, but the closer you have it to the hinge the more unstable it becomes in wanting to open the hinged boards through over balance, so somewhere near the middle is fine. <br>E must = or &gt; the length of the lower hinged board, ( I made mine 228mm plus 20mm extra for mounting the motor, so like 250mm total ) but having a longer top board is just a waste of wood and adds unnecessary weight. <br>F, (basically the altaz mount) is just used to rotate to a part of the sky you're interested in. <br>The entire contraption is mounted on a tripod and that tripod mounting is used to aim at the south pole and once set south you dont touch it again, hence the need for the altaz to mount the camera so you can rotate to different parts of the sky. <br>
Hey! <br>Thank you very much for the answers. <br>I was afraid it might be too complicate to describe. <br> <br>Ill post pics of the results if I can get the gismo going. <br>Still waiting for the motor. It may take some time this time of year. <br>For interest sake, where did you find it?
You're welcome, I got mine at Yebo Electronics Boston Branch, R115. It can go either way CW or CCW on startup so you just need to check which way its going when you switch on, if its the wrong way then you just flick the power switch till it goes your required direction. Yebo electronics link http://www.fort777.co.za/index.php?main_page=product_info&amp;cPath=269_270_423_1093&amp;products_id=6939&amp;zenid=u2puk32cu2lu0j5qqch6vf0ete3l13cb
Hi <br>This is awesome. <br>Im building it as of today. Already made a few amateurish shots on my canon sx 40 mod with chdk. were ble to get Jupiter and its Galilean moons with it alone. <br>Also from South Africa, so this is too good. <br>Anyhoo. <br>Can you provide some info on the cam? <br>I don't exactly understand how big to print the cam. Im using same parts and specs as you. The 65mm square' don't help me much, since I have no idea what to do with it. <br>Any help will be greatly appreciated. <br>Thank you. <br> <br>
hiya, when you print it out, the pic must be 65mm x 65 mm on paper, the red lines on the rhs and bottom edge with arrows give the place to measure the 65mm. I use Irfan view and insert 6.5 with aspect ratio in &quot;custom check block&quot; in print settings. I almost read someones mind once with a Panasonic FZ10 <sup>(12x)</sup> and I thought that was serious zoom, but a Canon sx40 with 35X zoom... you could probably see what brand of cigarettes they smoke on Jupiter. :)
Thanks! I have been wanting to make one of these gizmos since I first saw one in S&amp;T. It's about time I got my butt in gear. I like the simple camera mount yours has. Thanks for the inspiration. I know my old Pentax 35mm SLR will work but I do have a point and shoot digital. . Can you explain this CHDK thing? Also, how long are your exposires? I figure a 10 min shot would open the boards only 2.5 degrees but your photos show them much wider than that.
You're correct, a 10min shot would only open the boards 10mm = 2,5 degrees, my pics arent actual working pics but merely glamour shots for the 'ible. <br>Due to my light polluted location I can only get about 2 min shots before the orange haze sets in. <br>CHDK is for Canon PowerShot series cameras only and because its software you dont need a remote unlike DSLR's where you have to use either a cable or an IR remote. <br>Basically you load the software onto a SD card and then run a script within that enviroment which manually overrides the shutter timer. Its fully reversable, when you switch off the cam all settings reset back to factory. There somewhat of a learning curve with lots of reading, site here..http://chdk.wikia.com/wiki/CHDK <br>Theres a list of supported cameras on the rhs of that website.
WOw.. really aowsome.. i have been just thinking ... who to track starts for loooonog exposures.. i tried at my end.. always either star trails are too long.. or environment becomes too bright.. <br> <br>I'll do this practice in my earliest free time :) thanks
Woah! I never knew about this. So cool! Great work, you should post some more exposures!
Thanks, have to delete a lot cos Im still learning the tricks. <br>Naturally, building one of these devices will ensure cloud cover for some time. :)

About This Instructable




Bio: general bloke type of tinkering
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