Stabilizer Home

Please note, occasionally I refer to diagrams which at this stage do not exist. In the fullness of time I will get to draw some.

I once met a guy who claimed to have such a steady hand that he didn’t need a tripod or any other method of stabilization.

A fairly unlikely scenario, I think, after viewing dozens of amateur videos at club meetings. And they are the ones who are a little bit serious about their work. What about the average home videographer?

Ever since movie photography began, cameramen looked for the most stable way of using their camera. Mind you, they probably didn't have a choice. I guess the cameras of the day were not exactly portable. But portable they became.

It was an innovative cameraman, "Billy" Bitzer who was the pioneer of mobile cameras. By mounting units on horse drawn carts and everything else that moved, he was able to produce the shots that held the audiences of the day spellbound. He went on to work with D.W. Griffiths on many epics. Nowadays, it’s normal to get mobile shots from all manner of moving platforms.

It was in the early 1970’s that another innovator, Garrett Brown, invented a device that gave the camera even more freedom and is now commonplace in most movies. Look at the credits and you will generally see the Steadicam operator get a mention. Ultimately, some of this technology had to rub off on the serious amateur, and it was the early 1990’s which saw the release of the Steadicam JR. which gave the average videographer the chance to do what Hollywood has been doing for years.

I don’t know whether you have noticed but you can shake a camera about in different ways. By displacing it vertically or horizontally but keeping it level, the actual movement of the image is negligible, providing , of course, that the subject is not extremely close. Just think, if you were filming the distant hills. What difference would it make if you were standing at ground level or on a three metre ladder. Very little. And likewise horizontally. If you were to walk three metres to the left not much would change. So a bit of movement, provided the axis doesn’t alter, is not going to ruin your magic moment. But what if we rotate the camera about some central point. Check the diagram if I am not making myself clear. What we are doing now is pretty much panning and tilting. Now we have images dashing across or up and down the viewfinder. Different story now. So it’s rotational instability that we have to worry about.

Let’s cast our minds back the age of the dinosaurs when Super Eight cameras roamed the earth in large quantities. Remember them?, they were the ones with the handles attached to the bottom of the camera, usually with the battery compartment built inside. They were a bit heavy too. If you’re a dinosaur like me, and you can remember using these things, you may have noticed that the stuff you took was pretty stable. Heaps better than what you can do with your little JVC palmcorder. I wonder why that was?

A few centuries ago a certain Mr. Newton discovered that things that aren’t moving show an inclination to stay that way, and if you try to make them move you will expend an amount of energy just getting them going. This tendency for things to stay put is called Inertia and it is proportional to the mass of the thing you are trying to move. The heavier the object, the more the inertia. A camera, like all other objects has mass, and therefore its resulting inertia will give it a tendency to stay still. Unless, of course, if you try and shake it about! A heavier camera with more inertia is harder to move so it will have more stability. But that’s only half the story. A quick look at the diagram might help at this stage.

The centre of gravity of an object is the point about which its mass is evenly distributed. An object that is supported at its centre of gravity tends to remain stable. Take, for instance, the tightrope walker with his long pole. The pole is balanced at its centre of gravity and, depending on the pole length, is stable enough to keep the walker upright. The centre of gravity of a camera is somewhere inside, about the middle. The tripod mounting thread is approximately below it. On an old Super Eight camera they put the handle underneath with the additional weight of the batteries inside. This tended to pull the centre of gravity down into the handle, close to where we were supporting the camera. A very stable position. Now let’s look at our nice new camcorder with its strap on the side. The support position is to the side of the centre of gravity making it inherently unstable and requiring you to use the other hand to support the camera as well. (which you should always do).

To sum up: Our nice lightweight camera with the strap on the side is not doing us any favours when it comes to stability. Is there something we can do to improve it?

Steadicam JR

Since the release of the JR., other manufacturers have followed. Some work, some don’t. The price is generally and indicator. As with any product, there will always be the DIY amateur who for reasons of economics or just plain curiosity, decides to build his own. DIY’s come in all shapes and sizes. I have seen some home built stabilizers that would compete with the real thing, and I have seen others that…….well, best left unsaid. No matter, they all have something to offer.

This page is dedicated to the experimenter/fiddler. Primarily devoted to stabilizers, but also other bits and pieces related to the videography field, I hope to draw out of the woodwork some of those amateur engineers quietly toiling away in their garages and sheds.

My own experience goes back a couple of years after seeing the JR. demo video at the club and wondering how the darned thing worked. It looked simple enough, "elegantly simple", as Garrett puts it, but trying to duplicate the results is another matter.

Maybe it’s my engineering skills (or lack of), that has allowed me to accumulate a big box of discarded ideas before arriving at a workable device, ironically looking strangely similar to the original JR. Never mind, the learning curve still makes it worthwhile to be able to say, "I designed it, I built it, and it works".

The stabilizer stick.

The stabilizer stick.

Everyone is entitled to do something dumb once a year and my extravagance is to run the Perth City to Surf race which is 12 kilometres from the central city down to the beach. Some of this is uphill and not much is downhill. At least that’s the way it seems!! On one occasion I had one of those plantar things removed from my foot and was unable to run. It didn’t mean I couldn’t walk.

This was my first experience with videoing on the hoof. To make life easier I attached the monopod (compressed of course) to the camera and then improved the balance with some small weights taped to the bottom. The results were better than satisfactory. Getting along with the rest of the 8000 (at the start anyway) added some life to the video that couldn’t be got by being just a spectator and I made a mental note to make up something a bit more permanent when time allowed. Some of the blokes in the video club have mentioned trying the same idea. What a pity they don’t put these things in video mags.

The Fullness of Time is an amazing thing and it wasn’t until recently that The Stick emerged as a practical item. (check the photos) Now I can get about and take pictures without the inconvenience of a viewfinder stuck in my eye. The other advantage of course is that videoing is once again a one-handed affair. The little clip on the battery allows the mounting of a standard 35mm release cable. The one I use has a bulb on the other end and allows me to walk around, hand in pocket, a bit more unobtrusive than normal. The handle allows the camera to be held at any angle, over fences, up in the air, and interviewing becomes more of a face to face exercise, as it should be. Everyone should have a stick, it gives a freedom otherwise unobtainable with a palmcorder and it’s real easy to make and cheap.

The gimballed stabilizer.

The stick is a great gadget for everyday videography and I wouldn’t be without it but if you are a real stability freak it doesn’t take long to realize that there is a better way. The problem with the stick is that it is still attached to the operator so when you move, it moves. Garret Brown woke up to this a long time ago when he devised a gimbal mount for cine cameras. The big drawback with gimbals though is that they require a bit more engineering. Before I get into how the Steadicam style of gimbal mount actually works, it’s necessary to go back to physics.

Remember when we discussed inertia earlier. What I was referring to applied to objects moving in a straight line, but it equally applies to things that rotate. A wheel on an axle has rotational inertia.

But it doesn’t have to be a wheel. Anything rotating about a point shows the same characteristics. Take, for instance, the tightrope walker. That pole is not for decoration, it plays an important part in keeping the bloke up there! What he has done is select a pole that is as long as possible to maximise the inertia but not so long that it is too heavy to carry.

This is what happens with a gimballed stabilizer. The gimbal forms the axis, with the balance weight at on end of the pole and the camera at the other end. Of course we don’t put the camera and the weight at a similar distance from the centre because that would make the weight the same as the camera. To make the thing practical, the camera end is a lot shorter and to get the thing balanced we multiply the weight by the distance in each case and make sure they are the same. They call this the principle of moments and you probably covered it in high school science.

Let’s go back to rotational inertia for a minute. The formula to calculate it is:

Where I   is rotational inertia.
            M   is the mass of the object
            R   is the radius of rotation.

Those of a mathematical persuasion should immediately see that the inertia is proportional to the square of the radius. So the trick is to put the weight as far away from the centre rather than increase the weight. This applies to the camera as well. Now we have some conflicting conditions. On one hand we have the formula telling us to move the camera out from the centre to increase the inertia and make

it more stable. On the other hand if we do that, we have to increase the balance weight or move it further out as well. Carried to the extreme the thing would be either too long to get about with or too heavy. So it’s necessary to come up with a total weight that is comfortable to carry around and work backwards to the dimensions. Once I cottoned on to this stuff I made up a spreadsheet in Excel so I could plug in different dimensions and see what happened to the weight, inertia, etc., I might include it here at a later date. (that means I can’t find it!)

A perfectly balanced system can be rotated to any point and it will stay there. Not much good in a stabilizer because if it does move, we need to get it back to vertical. To make it work properly we need to add just a tad more weight to the balance so it will always return to the vertical, but not so much that it will oscillate like a pendulum. In the Steadicam documentation they refer to the "drop test". This test states that the system should be removed from its balance position to, say, 45 degrees off vertical and let go. It should return to rest in about 2-3 seconds. That’s very slow and it means that all the forces are just about in equilibrium leaving only the friction in the pivot point. And what a headache that can be!!

Details of the gimbal mechanism.

The function of the gimbal is to isolate the operator from the camera. This means that the gimbal must be free to rotate in any direction. Technically these directions are referred to as the X, Y, and Z axis.

The X and Y pertain to the vertical or tilt direction and the Z pertains to horizontal or pan direction. As well as this the gimbal must be almost frictionless. This is where all the headaches come in. The first gimbal I made was from a wacky bracket, a kind of ball joint which I polished. It seemed at the time like the ultimate solution. Then I graduated to plastic pipe and steel screws with the thread smoothed down at the point of support. Now I am using steel saddles with knife edge holes, high tensile grub screws to adjust any slop, and two roller bearings for the Z axis. Check out the drawings and photos for details. Dave has just produced one with needle point adjustable bearings, not unlike the balance wheel of a clock. It works pretty well and is probably the way I will go. The geometry of the structure has to be exact as well or the camera will re-adjust its tilt when rotating in the Z axis. So all this means building to very high tolerances, not the easiest thing to do in the average garage workshop. This is not to say that it can’t be done, just you can’t do it in a hurry. Dave and I have spent probably the last six months messing around with gimbals. Every problem that we have had has come back to the gimbal.

There are some other sites on the web featuring home-made stabilizers. Elsewhere on this page you will find some links. There seem to be two main designs, those based on the original Steadicam JR, and those along the lines of the Glidecam. The Glidecam design takes a lot of the hard work out of gimbals by using commercial roller bearings in a different configuration. At present I have opted for the former as it seems to put a lot less strain on the hand. Some time in the future I will find out if this is so.

Back in the days when I was a kid we used to play on the see-saws in the park. Whatever happened to see-saws anyway? One of the things I, and probably every other kid, did was to stand astride the centre of the see-saw whilst the other guys were balancing it. If you’ve ever done this you will know that the force needed to tilt the see-saw

either way was quite considerable. Partly because of the inertia of the two blokes on the ends and partly because of the leverage required so close to the centre of gravity.

A gimbal stabilizer removes the operator from the camera so the camera is free to go wherever it wants. Now, usually this is nowhere because of the inertia of the system so you need to control it somehow. To do this you need to grip it lightly (remember I said lightly) with the fingers and thumb just above the gimbal. This will give you some control over the camera but like the see-saw in the park the effort will be damped by the close proximity to the centre of gravity and thus you wont be transferring any shakes from your control hand back to the system.

Adjustable base and leveling of the stabilizer.

One of the things that doesn’t come with commercial stabilizers is some way to start and stop the camera. A pretty fundamental thing when you think about it, after all not many people want to go out and just walk around with a camera. I saw something called a Zoom Handle which connects to the LANC socket which is a serial interface and is capable of controlling many camera functions. That’s if you have a LANC connector of course. Some cameras have other control systems. I toyed with the idea of using the infrared remote but I ran out of hands. Currently my unit uses a 35mm shutter release cable fitted to a little home made bracket on the camera near the button.

The business end of the remote is mounted on a bracket just above the gimbal and is operated by the controlling hand. It’s a cheap and cheerful method until a better one comes along. There are ways of making LANC controls which don’t cost the earth. Dave and I are looking at making something up using the popular PIC series of micro-controllers. They can be programmed via the PC using BASIC programmes available on the web. That’s the good news, the bad news is that all the info I have seen is for the Sony D8 and may not apply to other cameras.

Stabilizers