Hi, this is Wayne again with a topic “Weekend Project: Perfect Astrophotography”.
This weekend we’re going to try something a little bit different if you ever try to take pictures of space. If so, you know how difficult it can be. You have to use long exposures in order to capture the light from the stars, and if your camera is not tracking the sky, then you end up with smears of light in this weekend. Project by gary sironik we’ll be building a hinged sky tracker to track the stars with the movement of the earth. In order to build this project, you’ll need these parts and tools.
You can use a prototype board to make things tidy, but there are so few parts that you could just solder them into each other, as shown in the schematic. Just make sure you heat shrink any bare wires to prevent short circuits solder. The two conductor, cable to the rca plug and connect it to your circuit, where the schematic indicates the dc motor will be. This lets you easily unplug the electronics. When you need to you’ll connect the motor and rca socket later. It might be tempting to substitute a regular 500 ohm potentiometer for the one specified, but you’ll need the precision of the multi-turn potentiometer.
The regulator circuit is housed in a project box. You can use something store-bought, but we’re using one from laser-cut. Plywood you’ll need to drill three holes in it. One for the power switch another for the wire that connects the electronics to the motor via a standard, rca jack and a third hole to access.
The potentiometer adjustment carefully position the pot so that its adjustment screw is accessible through the hole you drilled and glue the part in place for the mount to track accurately. The drive rod needs to be curved into an arc with a radius of 7 inches. It’S difficult to evenly bend a short length of threaded rod so start with a piece. That’S at least 12 inches long use a compass to draw the required arc on a piece of paper.
Taped to a flat surface then place the threaded rod onto the paper and gradually bend it until the curve in the rod matches the one drawn on the paper. Finally use a hacksaw to cut out a four to five inch section from the rod. A segment of this length will give you around an hour and a half of uninterrupted tracking you’ll need to drill a few holes in the lower half of the hinge begin with the most important one.
A 3 8 inch hole for the motor shaft position. It one and a quarter inches from the center of the hole that the curved rod passes through then drill and tap a pair of holes for mounting the motor. The hinge tracker will sit on a standard, photographic tripod, so you’ll need to drill and tap a quarter.
Twenty hole centered roughly one and a quarter inches from the hinge, pin edge, cut a four inch length from a piece of one and a half inch hardwood stock then lay the screw threads of the hanger bolt across it and cut it in half. At a 45 degree angle, just beyond the end of the bolt, this piece will become the mounting block and you can throw the other one away screw a quarter. Twenty hanger bolt into the flat top end of the block, then use epoxy to glue the angled end of the top half of the hinge centered roughly two and a half inches from the pin edge. A key part of the drive assembly is a nut that couples a large gear to the threaded. Rod, use a blind well nut for this purpose, prepare the gear by inserting the blind well nut and trimming off its rubber flange. You may need to enlarge the hole in the gear slightly with a round file for a good tight friction fit now connect the motor leads to the rca jack.
The motor needs to turn counterclockwise if you’re in the northern hemisphere or clockwise, if you’re in the southern hemisphere. So you may need to reverse the polarity of the motor leads to get the motor to turn the correct way if the motor runs the wrong way. The tracking platform is literally worse than useless, so make sure you get that part right attach the socket to the angle bracket and mount on the hinge now, it’s time to put it all together, mount the motor on the hinge and fit it with the small gear Attach the threaded rod segment to the last hole on the top half of the hinge using a pair of nuts and washers, you may want to use a brass acorn nut on top just to make it look a bit nicer. The threaded rod should pass through the corresponding hole on the bottom half of the hinge, without binding next thread on the large gear.
When the hinge is closed, it should mesh with the motor gear. You may need to add a teflon washer beneath the large gear to better align your gears. Your alignment may vary now. The hinge tracker is complete.
Before attempting your first photograph, you have to adjust the motor speed so that the large gear turns at exactly 1 rpm. The easiest way to do this is to mark one of the gears teeth with a felt pen and add a small tick mark to the base, run the motor and start your stopwatch, just as the marked tooth aligns with the tick after exactly two minutes. Stop the motor and see where the marked tooth is relative to the index mark for increased accuracy. Let the motor run up to five minutes, adjust the multi-turn potentiometer to speed up or slow down the motor accordingly and repeat the test until the gear is turning at the correct speed to take photos with the tracker, you first have to align it with the north Celestial pole for wide angle, shots simply sight along the hinge and aim at polaris the north star, if you’re using a longer focal length lens or shooting exposures more than one to two minutes. Long you’ll need to be more precise to accurately position the tracker we’re going to use the viewfinder on the camera. First, we’ll need to align it to the hinge’s axis of rotation side in a star along the hinge and adjust the camera on the ball mount until the same star is centered in the viewfinder after the star is centered swing, the hinge through a 180 degree arc And see if the star moves in the viewfinder, if it does adjust the ball, mount and swing the hinge again until the star stays centered through the swing.
Now that the camera is aligned with the hinge move the tripod, so that polaris is centered in the viewfinder swing the hinge again and make sure polaris stays centered. Once you swing the camera through the arc and polaris doesn’t move you’re free to position the ball mount at whatever heavenly body you’d like we really love the simplicity of this build, especially when you consider the quality of the photos that you get. We’Ve noticed, though, that it’s a little bit difficult to bend that threaded rod and get a consistent curve. So we’re reaching out to you if you have any better ideas about how to bend that threaded rod and get a consistent curve or if you have an even simpler idea for the entire mechanism, be sure to. Let us know in the comments, thanks for watching and we’ll see you in the next weekend project, if you liked this video subscribe to our website or send us a comment on facebook or twitter be sure to check out our other project videos or visit us on Makezine.Com .