Making A Camera Dolly Fun & Interesting
In two recent videos, I used a homemade dolly to pan the camera while I did the work. This is a technique often used on TV and in movies, and it’s something that I’ve wanted to do for a while. As I get more experienced at making the videos, my standards have gone up. Not only that, I want to do things that will not only make the video more interesting to watch, but make the process more engaging for me. Doing the same things over and over can be fairly boring, so I like to do something special in each video.
To start this off, I have a short video showing the highlights of the dolly and the motor used to pull it:
Here’s the finished unit:
The dolly can be set to run straight, or follow an curve. It doesn’t use a track, instead it rides on any smooth surface.
First thing I did was go to a thrift store and buy a pair of roller blades. These are usually in stock and almost always have wheels with very little wear.
The front axle is steerable, so it needs a pivot point and a way to attach it to the dolly platform. I used a 1/4″ hanger bolt for this:
The axle shaft is just a piece of 1/4″ threaded rod that has been set into a groove cut in the bottom of the axle. Regular nuts space the wheels away from the axle, and lock nuts are used at the outside to ensure they don’t come off.
The dolly platform is just 1/2″ plywood and needs to be cut out to allow the front wheels to pivot:
A 1/4″ hole is drilled for the hanger bolt in the front axle.
The rear axle is made the same way, but is just glued to the dolly platform:
The axle shafts are glued into the grooves with epoxy.
I made two points on the dolly to put cameras, one in the middle and one on the end. To attach the camera, I made these simple knobs from 1/4-20 bolts, nuts, washers and plywood disks:
A lock nut in a counterbore hold them in place from the top, but allow them to turn freely.
To raise the camera up and change the angle, I figured an articulated arm would be a great addition to the dolly. I did want to keep it simple, but strong enough to support my heaviest camera.
The first step was to make a block that would screw onto the dolly at the camera mount locations. To do this I drilled a 7/8″ counterbore most of the way through the block for a t-nut:
A 5/16″ hole was then drilled through.
The t-nut is epoxied and pressed into the counterbore and is flush on the bottom of the block:
The arms are next and those are made from strips of spruce cut from a piece of well seasoned 2×6. To make sure that the holes in both arms are the same, I used a drill bit to pin them together while drilling the other 1/4″ holes:
The arms are attached with 1/4″ carriage bolts, washers and knobs.
Next, I got started on the camera mount and it’s just a piece of 2x cut to size with a pair of holes drilled. The bolt that holds the camera is a piece of threaded rod with a nut and wing nut jammed on one end:
A lock nut is on the other end and it fits in a 5/8″ counterbore. There’s just enough thread sticking out to attach the camera.
With the camera mounted, you can see some of the range of motion:
Set up on a piece of plywood for a test shot:
The tugger is about 16′ away to reduce the noise.
With the dolly more or less finished, I started thinking about how I would power it. The tricky part is to make it move slowly and smoothly.
My first thought was to make it work with just gravity, with the dolly rolling down an incline. The problem with that is how to go about making it run slowly and regulate the speed. That’s something I want to come back to in the future, but for now I thought that a good, simple way would be to pull it with a string and a cordless drill. To use the drill, I had to make a holder and that starts with a piece of 2×8 big enough for it to fit on:
I added a block in the crook of the handle at the back.
And a block with a t-nut and bolt to press in the trigger:
A few other parts were added to guide the string and hold the drill tight:
A bolt was chucked in the drill to act as a spool for the string to wind around.
I did a test run out back with the camera directly on the dolly and the dolly set up on a piece of melamine on two saw horses:
The melamine is elevated on this side so that the dolly will be pulled uphill. Pulling it uphill takes away the possibility that it would free roll.
The tugger set up:
The arrangement worked well, but I did have to raise the camera up, otherwise the melamine was in the shot. An articulated arm would be a good addition to the dolly, and I get to that later in this article.
Tugger Version 2
Although the drill worked well, it was really difficult to exactly control the speed, so I bought a power window motor at a surplus store for the next version of the tugger. It came with a shrouded connector that I had to cut open to expose the contacts. I soldered two wires directly to it:
To form a spool, I drilled a 3/4″ hole in a 1″ dowel to epoxy onto the output gear of the motor.
I figured the 1″ dowel was close to the perfect size, but I could always slow the motor if I need to:
A test to see how it works went well and I could go ahead with making a holder for it.
Nothing fancy here, just a piece of 2×3 and some plywood to mount the motor on:
I added a box for the 12 volt battery and experimented with a resistor network to slow the motor.
To keep the string neatly wound on the spool, I added two pieces of plywood with a small gap between to guide it:
With the resistor values figured out, I wound up with three speeds: slow, medium and full speed. I added two switches to select these speeds. The switches just short the resistors to increase the voltage. It’s worth mentioning that the resistors are burning off a lot of power and will get hot or can burn out. I used what I had on hand (10 watt resistors), but I figure it will be ok to use for short runs. Higher power resistors would be best and last longer. You can make your own with nichrome wire from a broken toaster or hair dryer. I’ve also used mig wire for this. In all cases, there will be heat and it can be enough to burn skin or ignite wood.
Also worth mentioning that a battery is the best way to power this motor, as it’s more portable and the motor draws a lot of current. I measured it running at full speed drawing nearly 5 amps at 12 volts. That’s 60 watts, so it would take a fairly hefty power adapter or power supply to put out this much juice.
A computer power supply may have enough current available on the 12.6 volt rail, but it’s best to check the specifactions on the one you would use.
The finished tugger. I screwed pieces of aluminum over and under the resistors to hold them in place and help drain off the heat they produce:
Although this works well, as I mentioned in the video it does make some noise and it is somewhat jerky. I may take the motor apart to see if I can find out what is causing the jerky action, but the noise may be nothing worth worrying about. I can place the unit far away, and there are usually sounds (voice-over, music) in the recording that will easily mask it.
Audio for my videos has always been a big problem for me and I have spent (wasted?) a lot of money on it. About a year ago, or more, I bought a wireless lav mic set that I used in several videos. Aside from the massive improvement to the audio overall, there were some significant issues. First, there was an interference problem. When the transmitter was near something metal, it would produce static. That causes a lot of problems and made me paranoid about using it. Second, I couldn’t find the ideal way to connect the receiver to my camera. Since it is actually a presenter set, it was made to be connected to a PA system via a balance output (xlr). My camera has a 3.5mm phone connector for a stereo microphone, and this mismatch caused a clipping problem that I could not solve. These problems plus a lack of mobility and inconvenience has kept me from using this setup. A shame, since I am really impressed with the microphone quality.
Back to the present, and I’ve acquired another wireless mic. This one is made for my camera, by the camera manufacturer. Should be aces, right? Well, not quite. The mic sound pretty good, but is bulky. It has the transmitter integrated and uses a AA battery to power it, so it is rather large. I thought that it wouldn’t be a problem when I bought it, but found that it was really too big and drooped or fell off too easily. Here’s a link to the details on the mic.
So, I have an AKG wireless presenter set gathering dust and a nearly useless WM-V1 mic, but they both have features that are very desirable. The presenter set has the amazing lapel mic, and the WM-V1 mic has clear, interference free transmission, plus is a lot more portable. Time to draw on the disassembly skills learned taking apart all of my toys when I was a kid, and attempt to borg the two together.
I must apologize for the lack of pictures. To be honest, I didn’t think it would be as easy as it was, and figured it wouldn’t work at all.
First thing I did was to figure out how to take apart the WM-V1 mic. Easy, just two screws inside the battery compartment and I could remove the cover, exposing the mic. I turned the unit on and measured how much DC bias was going to the mic capsule: 2.2 volts, the same as the AKG transmitter. Good! They match.
Next, I took the mini xlr connector off of the lapel mic:
And removed the mic capsule from the WM-V1.
I could then fish the lapel mic lead into the WM-V1 and solder it directly to the mic wires, making sure I had the polarity correct:
Before putting the cover back on, I tested it – flawless!
When you add the cost up, it’s still cheaper and more compact than one of the better wireless mic sets, so a good investment and gamble all round.
Since I had all four of the cameras I’ve used for video out in my shop, I thought I’d do a quick side by side comparison. My overall impression is that there isn’t a huge difference in picture quality, but there is more of a difference in functionality and ease of use.
The camera I use mostly now is the Canon Vixia HF G30. I bought it almost a year ago, mainly because it has a wider angle lens built in. My previous camera needed a conversion lens that added a lot of distortion, not to mention weight to the camera. The G30 has other desirable traits as well, including the capability to record at 1080/60p. I have not used that functionality yet, but I will at some point – it’s great for slow motion.
Here’s how the G30 looks:
Mostly, that is, since I bumped up the exposure on the finished video to try to brighten other scenes. I looks overexposed in the video, but wasn’t in the raw clip.
Another great feature of this camera is its low light capability, making it suitable for situations where adding more lighting would be impractical. My shop is well lit, but the camera would work well with all of the lights turn off and just natural daylight coming in through the widows and doors.
Before the G30, I had another Canon – a Vixia HFM50. As mentioned earlier, the biggest (only?) drawback with this camera was how narrow the view was. Picture quality and low light performance is nearly as good as the G30 :
Next, my first camera used for video, the Nikon Coolpix S8100 . I made a lot of videos with that camera, and still use it now. I always thought that it had a much narrower view than the Canon, but as you can see in the pictures above, the S8100 is a bit wider.
This camera has decent picture quality (for video, much better for still photos), but has dismal low light performance. It’s also prone to a “lens error” problem that I’ve encountered and dust can easily enter it through the lens opening and closing. A future project is to attempt to disassemble this camera to clean the dust off the lens.
Finally, a camera that I rarely use for video, my Nikon D5100:
The picture quality for this camera is great, and it does well in low light, but it’s just too much of a hassle to use, especially if you are doing a build video with 100 or so shots to set up.
Of course, as shown in the samples, you can do a lot more with a DSLR camera because you can change the lens.
I bought the D5100 after my D40 dropped on the floor and the built-in flash stopped working. It was on sale, body only, and would accept the lenses that I already had. I was also curious about shooting video with a DSLR, and the D40 doesn’t have that ability. I will probably use it for video more in the future, in particular using it with my wide angle lens.
In conclusion, my opinion on the point-and-shoot / DSLR vs camcorder for video has me firmly in the camcorder corner, which makes sense, since they are video cameras. I will say that a single DSLR with a decent lens will double for a video camera when you also want really good photos.
Of course, another option is a cheaper camcorder and cheaper point-and-shoot camera, if you want to do both. I really like the photos I get from the Coolpix, and the video from the HFM50. Both are very easy to use and can be had for less than a lower cost DSLR.