Simple Camera Dolly for Time-lapse Photography

As an amateur photographer, I enjoy taking pictures of the Northern Lights. However, still images can not render the dynamic of the aurora. To solve that problem, I decided to make time-lapse videos of the lights. They turned out great but I needed something else: a mobile point of view. This is why I started building my own motorized camera slider.

The low prices and ever increasing variety of micro-controllers have triggered a revolution in a lot of domains. Photography is one one them. Motorized camera sliders have popped all over the internet, each with their own length, motors and circuits. However, adding complexity usually increases prices. As I did not want to spend too much on the build, I decided to keep it as simple as possible.

This slider uses a DC motor, has a single speed (about 2 hours from one end to the other) and does not use any electronics.

The Rail

The main part here is the rail. As I was looking for extruded aluminium, I came upon a straight clamp for circular saws. I only kept the aluminium rail ($35).

Moving Parts

I ordered the motor, belt and gears online. Here's the list of parts I got from sdp-si:

Ball head

To keep the slider balanced, you will need to keep the centre of gravity as low as possible, that means a short tripod head. Ball heads are a great option since they don't have a handle and they can quickly point in any direction.

Tripods

If you want this "rising" point of view in your videos, you will need to start low and finish higher. The rail will need to be positioned at an angle. The solution I chose was to attach quick release plates at both ends of the rail and buy 2 cheap tripods. That way, you can still disassemble the support and keep a lightweight and transportable slider.

Ball Bearings

You will find those at the local skate and roller blades shop. You will need 6 of them. You can probably find an 8-pack for $10.

The carriage is made out of wood. If you have access to metal milling machines, you could make it out of aluminium. I used pine because this is a prototype. Use some hardwood for greater strength.

The width of the carriage is the same as your rail.

Cut 4 notches in the corners for the wheels (ball bearings).

Drill a 5/16 hole at both ends for the wheels axles.

Assemble the wheels using:

• 2 5/16 bolts
• 4 bearings
• 4 washers
• 2 lock nuts

To prevent the carriage from rolling off the rail, we'll add guides on both sides. I used 1/4 plywood.

The carriage is not yet completely secured. We need to keep it in close contact with the rail. We'll add 2 more bearings under the carriage using:

• 2 5/16 bolts
• 2 bearings
• 2 washers
• 2 lock nuts

To attach the belt, I used 3 dowels. This system clamps the teeth together and prevents it from sliding. It is also very easy to attach and remove. Locate the middle of the belt and attach it to the carriage.

An important part of the design is to keep the belt under tension so that it doesn't slide against the teeth of the gears.

To build it, I used aluminium railing. I could not find any U shape rails so I attached 2 L shaped pieces together. A screw with a flat head is fitted on the rails. A small hole is drilled at the base of the screw to attach a spring to it.

Using a small machine screw, assemble the gear between both sides of the U shaped rail. Use a tap & die set to make a thread in the aluminium.

The motor is a 0.5 RPM (rotation per minute) DC motor. It requires 6V to run. You don't need any electronics here, just get a battery case which can hold 4 AA batteries and solder it to the motor. My case has a switch included which makes it even more convenient.

To attach the motor, you will need to drill a hole large enough to fit the plastic ring at the base of the shaft. Once in place, trace and drill 2 holes to screw the motor onto the rail.

You can notice on the pictures that I added an extra aluminium plate. This is because I needed some space to attach my quick release plate but I did not want to loose any rail length.

Once the motor is in place, you can fix a gear on the shaft using a tiny allen key (I had to make one myself).

To attach the quick release plates, you will need to tap a thread in the aluminium plate. The quick release system often has a pin to prevent rotation. Drill a second small hole for that pin.

Attach the plates on both sides of the rail.

Most tripods come with a 1/4" thread at the base. Drill a 1/4 hole in the carriage and countersink it from under. Try to centre the hole as much as possible

Use a countersunk 1/4" screw to attach the tripod.

If you already attached the quick release plate, remove the one on the opposite side of the motor. slide the carriage in and re-attach the plate.

We are now going to cut the belt at the right length. Place it around both gears and add some tension to it. Mark the belt and cut it. Use the belt attachment plate to hold it securely.

You can now pull on the belt and re-attach it to the motor's gear. The carriage should not be able to move from now on.

Start by setting your tripods at different heights. Attach the quick release plate on them.

Check the direction you're slider is moving when you power it on. Pull off the belt, move the slider to the beginning of its course and put the belt back on.

Put your camera on the ball head and attach your timer to it.

Aim at the scene you want to capture, start the motor and start the timer.

After about 2 hours, the carriage has reached the other end of the rail. My design doesn't have a limit switch so you'll have to watch it carefully because it won't stop by itself.

One thing to remember regarding the settings:

• Set the focus on manual to avoid any blurry image that would ruin your time-lapse.
• Set the exposure on "auto" otherwise you might get over-exposed/under-exposed images in your sequence.

Here are 2 videos. The first one was made to validate the set up. The second one was a test on the northern lights. Unfortunately the clouds rolled in at the same time.