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Saturday, February 7, 2009

••◊ Tracking shots

Last Wednesday I was asked by a friend of a fried how I created the illusion of motion in one of my bicycle racing pictures. Is it photoshop? Nope. The answer is a "tracking shot," also called a "panning shot." The idea is to move your camera along with the moving object. If you track well enough one slice of the picture will be in semi-focus and the rest of the picture will look like motion blur. You also need to use a slow shutter speed (a.k.a. dragging the shutter). Most often these pictures are taken outdoors in daylight so I use shutter priority mode with a really small aperature (f/22-ish on a sunny day). 1/60 to 1/50th of a second seems to work pretty well for fast moving subjects like bicycle racers. Background blur naturally occurs because the distance moved in the background is much greater than the distance moved by the subjects in the foreground (i.e. things further away move faster while moving a camera). Obviously the correct exposure time will depend on how fast your subject is moving. An Indy car would probably achieve this illusion with 1/250th exposures (speculating).

Let's look at a fairly good example. Notice how the two center cyclists are semi-focused and the outer extremes have a lot of motion blur? This comes from tracking the guy in the red, white, and blue jersey while clicking the shutter button. He's not really in focus, but relatively speaking he's razor sharp. The trick is to start your tracking movement *before* you click the shutter button. You can't click and then start moving. It just doesn't work. I also use one of the focus points in the view finder to align to the subject's head so I know where to keep him in the frame during the tracking.
So...sorry, no photoshop tips here. I did it all in camera and then just did the raw conversion.

What's cool is that this also applies to cinematography. As anyone who has dealt with 24P capture knows 24P is terrible at motion capture. However, if you track the moving object then you can avoid a great deal of motion blur and not make your audience sick with frame shudder. It works through the exact same mechanism. I was actually disappointed in No Country for Old Men when I saw Josh Brolin's truck come up the road with motion sickness inducing shudder. Usually Roger Deakins handles these things better. I also saw this issue in the Ace Ventura: When Nature Calls movie when they were doing fly over shots of the temple (as I roughly remember). I probably would have not realized the issue until I got into post too. Sometimes it's hard to tell how much shudder you have unless you blow it up to movie size.

Get out there an capture some stuff in motion. Looks cool.

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