Who could have figured that 150 years after the Civil War — that signature event in American History — would forever change the way we video editors approach a part of our craft?
Well, not the Civil War itself, but the Ken Burns documentary about it. For many, that program was where we learned about the power of using "moving stills" in a video project. Clearly the subject matter — the Civil War — didn’t have any usable footage available, since during the Civil War there weren’t any motion picture cameras! They hadn’t been invented at that point in history.
But still photography — as practiced by pioneers such as Matthew Brady — was developing during that era and there was a significant, but not unlimited, catalog of early photos available. Perhaps there was only a single photo available of a noteworthy general, perhaps posed as a part of a group shot.
Mr. Burns must have faced challenges like having only one usable image of a key historic figure — and an important copy point about that person’s role in the war that required many seconds of voiceover to make clear. Just tossing a static photo up, full screen, for 30 seconds would make for some pretty boring video.
He solved the problem, as others before him had, by using a technique known as "move on stills" photography.
Turning Static Images into Moving Pictures
The earliest move on stills work was undoubtedly just someone shooting a photograph from a tripod-mounted camera and figuring, "hey, this shot would be more interesting if I panned across it while rolling." And that’s still a useful technique today. If you have a photograph of, for example, a cheerleading team, and a static shot of the full team photo yields faces so small that nobody can see the kids — well, zooming in and panning across the faces in the shot will improve your video a lot.
But of course, the history of the human race is one of people always trying to invent a better way to do something, so it wasn’t long before folks got together to invent tools to make moving around still images more sophisticated. Welcome to the rostrum camera.
A rostrum camera is a very specialized piece of hardware that’s set up to perform moves on stills, video and a lot more. It’s a camera combined with a specialized motion controlled system that allows the operator to set up and re-create various combinations of pans, tilts, zooms, and camera rotations so that the operators can literally map out precisely how they want the shot to unfold.
In some mechanical rostrum camera designs, the camera head moves while the object stays stationary — in others the object is moved while the camera head remains fixed. Some rostrum camera rigs — particularly those used for motion picture work — are huge, occupying large rooms specially outfitted for this kind of photography. Others are more modest, perhaps consisting of a small, motorized platform under a fixed down-pointing camcorder. And of course, there’s today’s digital equivalent — "pan and scan" software.
Pan and Scan
Pan and scan software is a category of computer program that takes a digitized photo or other two-dimensional graphic and manipulates the computer file relative to the screen – rather than moving anything physical like a camera or motorized table.
Many of today’s modern editing programs —
particularly those that support keyframing can do pan and scan and recreate the effect of a rostrum camera, provided you plan your image capture properly. And make no mistake, careful image capture planning is important to succeed in this area. In order to pan and scan on a photo successfully, you need enough data in your scanned image so that when you enlarge it to enable panning and scanning inside the image rather than just across it – you can maintain the image quality.
You’ll know you’ve scanned at too low a resolution (undersampling) when you zoom in on the resulting file and get ugly, blocky enlarged pixels, rather than a clear image.
And you can overdo your scanning resolution as well. New users look at their scanner and see a top end scanning density of 600dpi or higher and figure that they’ll just scan at the top of the range and be safe. And they will. But they’ll also soon realize that oversampling eats up hard drive space quickly and, depending on how fast their computer’s processing system is, they might even find their software performing sluggishly. That’s because scanning photos at too high a density has a pretty dramatic effect on the size of the resulting files.
I remember getting called to help a person who suspected that their computer must have a virus only to discover that they had half a dozen still photos stacked on their timeline and each one had been scanned at 1200dpi then simply resized down to one inch by two inches for the composite. No wonder the system was performing sluggishly!
The goal is to scan at the right resolution for your desired result — not too high or too low — and your whole process will stay efficient.
The Beauty Factor
Okay, now you know how move on stills works and how to capture images so they process efficiently, the next step is to import your still captures into your timeline and decide how to move on them.
This is where your experience as a shooter will come in handy. When you’re behind the camera, you have to look at your scene and decide what’s important to your viewer. You need to figure whether the shot works as a still, as a pan, a tilt, or some combination. The same holds true for moving on stills.
My personal rule of thumb for doing a move on stills is the same as for any other shot I’d do in the field. I want to know where my shot will start and where it will end. And I want a strategy for getting from point A to point B.
In your editor, this is likely done by setting starting and ending keyframes. (And intermediary keyframes if you want to pan from Subject A to Subject B and then on to Subject C.) The best software programs will even support curved paths so that instead of moving around your image in straight lines like the path of a billiard ball on a table, you can gently arc between shots. Combine this with zooming in or out and perhaps even the kind of sophisticated speed ramping ability of some modern programs – and you can create virtual rostrum camera moves that equal the best in the business.
So if you have a project that requires you to incorporate still imagery into your video – fear not! You don’t need a room-sized rostrum camera to do sophisticated moves on stills anymore, just some digitized still photos and your trusty editor.
After all, video is imagery in motion, right?
Bill Davis writes, shoots, edits, and does voiceover work for a variety of corporate and industrial clients.
[Sidebar: Scanning Math]
The early computer industry established the native resolution of most computer files at 72 dpi (dots per inch.) At this resolution, a four-inch wide object scanned at a 1:1 ratio would occupy four inches on your computer or video screen. So if you’re planning to scan that photo of the local football team into your computer with an eye toward zooming in on individual faces, what kind of resolution setting should you specify for your file?
If you want to maintain full resolution while blowing up the screen image two times, you need to double the density of your pixels — or scan at a minimum of 144 dpi. (2×72). If you want to be able to zoom in 3X on your photo, you need to scan at a minimum of 3 times the native resolution – or 216 dpi.
Now most scanners have their own "native" settings in increments such as 150dpi, 300dpi, or 600dpi based on the scanners’ imaging array. In practice, it’s not critical to scan in precise multiples of the 72dpi figure – pick the closest native scanner resolution that’s above your target need and you’re good to go.
Oh, and don’t forget that while 72dpi is magic number for standard def NTSC TV — if you’re working with PAL, HDV, or Hi-Def sources, your numbers will vary!