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We love to give away trade secrets. There are three reasons for this. First, there are no secrets, really. Most smart art directors or advanced DP's who've been around for even a little while know their business, and already know these alleged secrets. Second, it ticks off the competition. Third, for those who have not had much experience in the things we write about, it teaches them about something they can really use in their everyday work. We hope. So, for those in category one, press on. Turn the page. You know this stuff. Category two members will be angry in a minute. Good. We like that. Category three'ers, you are about to get a nifty new arrow for your quiver. Now, tray tables up, and fasten seatbelts, please... |
What is Motion Control? |
| Not astonishingly, motion control means to
move things. Almost always this means in a repeatable, computer-controlled
way. You usually think of it as moving a camera, but it is also often used
to move the photographic subject -- and sometimes both the camera and
the subject simultaneously. Motion control is a technique and a method,
not a particular device.
Sometimes motion control rigs are small, like a tabletop graphics "down-shooter", and sometimes they are huge--big enough to throw around the heaviest of cameras, full-size small boats, and large model helicopters. Probably no two large systems are exactly alike, and no two have the same complement of software features, fixtures, gadgets and accessories, specialized lighting, space to shoot, and so forth. Making a good fit between the capabilities of the specific machine and its people to your visual idea will save you money and make better visuals. |
Motion Control Trade Secret Number One |
| Sometimes you don't need it.
Examine what you're trying to do. If it's a simple "flyover" of a dinner table setting, to reveal the product at the end of the flight, there's no need for that move to be highly matematically precise and computer-repeatable. That's a jib-arm shot. Muscles will power a jib just fine, and in a few takes you'll have the keeper. Jibs don't need re-programming or editing of the move if you want to change it, you simply move the jib differently. In contrast, it can take anywhere from a few seconds to a few minutes to re-program or edit a motion control computerized move. In that same dinner table example, suppose you make two passes, one with no product placed in, and a pefectly identical move with the product in its honored spot at the end of the move. Making a dissolve in post later will allow you to fade in the product while the flight is still underway. This is a delightful motion control shot. Very eye-catching. You'd never get it in a hundred takes manually while moving. Often a mix of plain old handmade jib-arm shots and computerized motion control shots will work out better than using only one technique for an entire series of moves. Use the jib for the simple shots and moves because it's quick and easy. Use the motion control system for the shots that really have to be perfect, or complex, or repeatable over multiple passes. |
Motion Control Trade Secret Number Two |
| Even with computerized motion control, simple,
elegant moves, with a slight curve to them, usually work best visually.
An audience can get disoriented if a complex dance of rapid twists and turns bombards them. Sometimes, however, that very effect is exactly what you want, such as the F-16 fighter pilot's view of things. Manually operated jib moves absolutely must be kept very simple. If you're using more than a light push with one finger to accomplish the move, chances are you'll be disappointed with the result. There will always be a pronounced "wander and wiggle" effect when moving more than one axis manually. This is where motion control really comes into its own. A move in multiple dimensions, executed perfectly, that needs to be easily "edited", will always be done better by a computer. In advanced driver software, you can even introduce some deliberate wobble to make it look like it was done by an imperfect human. This effect may fit in better with other shots in your show that were done manually. Very wide angles lenses--much wider than usual--usually enhance the effect of the motion. Often a 5mm or even a 3.5mm focal length will be right for truly exciting, extreme close-tolerance flybys. The closer you appear to be to imminent disaster, the more exciting the shot. Naturally, to get the most bang out of this effect, these wide angle lenses must have very small entry pupils. (Overall diameter of the front of lens.) A vital secondary benefit of using wide angle lenses is that they provide far greater depth-of-field with reasonable f-stops. Additionally, if you are pulling away from something less important to reveal the important subject, rather than advancing toward it, the effect is more visually exciting. The same is true if the close subject is entering the frame from the edges, rather than coming in from a far distance. If it's coming into frame from far away, one can see the subject and start to figure out what it is as it approches--removing the suspense, and eliminating the surprise. Remember the opening scene of the first "Star Wars", as the giant ship chasing the smaller one enters the frame close-aboard, right over our heads? The feeling of it's great size is enhanced by the constant surprise as it comes and comes and comes into the frame. |
Motion Control Trade Secret Number Three |
| At risk of stating the blindlingly obvious,
the whole point of this kind of photography is the motion itself.
This movement will draw and manage the audience's attention, reveal
things in a tantalizing manner, add some visual "eye food" to
intrinsically dull stuff, and play interestingly far longer on the screen
than static lock-offs, or run-of-the-mill zoom, pan and tilt shots.
Unless you've done a lot of this kind of thing, you'll have a tendancy to execute a motion control product shot as a standard three by four aspect ratio set-up with some motion added. No. Wrong. It's fundamentally different. It's better to think of it as an extremely long multiple set-up of conventional aspect ratio sub-scenes, with many smooth transition regions splicing everything together into one whole. The motion, complicated by the closeness, causes special problems with lighting. The camera's snout is often so extremely close to the subject that the shadow from the lens starts to become a big and visible problem. Soft lighting will help some, but key lighting from far greater off-axis angles than normal is the real answer. There is a tendancy to simply light everything from above with a big diffuse tent, or butterfly, but this causes other problems. For example, products in light-colored plastic bottles will have very bright "shoulders" and too-dark front labels. Tents also do not lend themselves well to stark or dramatic high-contrast lighting moods. Another problem with high-angle broad sources, like silks, is reflections in shiny subjects. Reflections easily "tuned out" in a conventional shot become impossible nightmares to tame when everything is moving a few miles. The only workable answer for a high-contrast mood is a relatively low-altitude, but well off-axis key and fill arrangement. Since wide angle lenses are most commonly in use, product backlight or rim lights will have to be managed carefully. Tiny french flags will have to be made from small pieces of black wrap or black cardstock. You will also find that small reflectors--often smaller than business cards--placed in a critical location will give you a fine deliberate highlight or fill where nothing else will do. |
Motion Control Trade Secret Number Four |
| A famous adman once said, "...the job
of advertising is to nail down an idea with a vision, or an emotion."
And that's what motion control is for.
Just imagine... It is Thanksgiving. A dining room table is exquisitely set. Dreamlike, the camera flies low, like a tiny helicopter, barely skimming the fine crystal and antique silver of our sumptuously laden feast. The scene is all about color, texture and movement. As our fanciful flight nears its end, the client's product dissolves in --- that's just one of the simpler things motion control can do. It is nothing less than a new way of viewing. |
