Instructables
Picture of Build a Motorized Barn Door Tracker...
...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/






 
Remove these adsRemove these ads by Signing Up

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.

Parts
  • 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.
wi11ywonka7 months ago

Hello,

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:

Nice to know:


  • M8 x 1.25 ...
  • M5 x 0.8...

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.

Thanks again!

Will

petercd (author)  wi11ywonka7 months ago
The M8 is 8mm dia and the 1.25 is the thread pitch, ie 1.25 mm per full thread
Alas you cant convert because then the other dependables wont match up.
I've seen imperial thread of 1/4" 20 on some of the other builds.
this site is using imperial threads in the build http://www.philharrington.net/scotch.htm
Ironwave8 months ago
Hi.
Thank you for the answer.
I got quite a bit done.
Few questions remain if you please.
http://www.instructables.com/files/deriv/FD1/9XIY/HPFZR1CA/FD19XIYHPFZR1CA.THUMB.jpg
A green- Is this length important, in example, must the camera sensor be directly over the hinge?
B yellow- I think this relates to question 1, my fault.
C blue- The length of upper part?
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?
E white- Length of the lower part.
F black-How do you know how many degrees to turn this?

I think F is maybe the only really important thing, the rest don't really matter?
marked.jpg
petercd (author)  Ironwave8 months ago
A & B not important, i just located them in the middle so I could easily access the thumbscrew underneath.
C can be as short as practically convenient.
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.
E must = or > 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.
F, (basically the altaz mount) is just used to rotate to a part of the sky you're interested in.
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.
Ironwave petercd8 months ago
Hey!
Thank you very much for the answers.
I was afraid it might be too complicate to describe.

Ill post pics of the results if I can get the gismo going.
Still waiting for the motor. It may take some time this time of year.
For interest sake, where did you find it?
petercd (author)  Ironwave8 months ago
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&cPath=269_270_423_1093&products_id=6939&zenid=u2puk32cu2lu0j5qqch6vf0ete3l13cb
Ironwave8 months ago
Hi
This is awesome.
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.
Also from South Africa, so this is too good.
Anyhoo.
Can you provide some info on the cam?
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.
Any help will be greatly appreciated.
Thank you.

petercd (author)  Ironwave8 months ago
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 "custom check block" in print settings. I almost read someones mind once with a Panasonic FZ10 (12x) 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. :)
cfs05278 months ago
Thanks! I have been wanting to make one of these gizmos since I first saw one in S&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.
petercd (author)  cfs05278 months ago
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.
Due to my light polluted location I can only get about 2 min shots before the orange haze sets in.
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.
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
Theres a list of supported cameras on the rhs of that website.
mfarooqi9 months ago
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..

I'll do this practice in my earliest free time :) thanks
audreyobscura9 months ago
Woah! I never knew about this. So cool! Great work, you should post some more exposures!
petercd (author)  audreyobscura9 months ago
Thanks, have to delete a lot cos Im still learning the tricks.
Naturally, building one of these devices will ensure cloud cover for some time. :)