Automatic point-and-shoot camcorders are convenient, but manual control of certain functions can do your videos a world of good.
If your first camcorder is a pricey model with more bells and whistles than the Santa Fe Railroad, you might face a daunting array of mysterious knobs, buttons, sliders and wheels. But if youve chosen a simpler appliance for getting started in video, your problem may be just the opposite: almost no controls at all. Every function is fully automatic and, to quote the ancient gag, nothing can possibly go wrong…go wrong…go wrong….
By "every function," we mean the controls for white balance, aperture, and shutter. (Though its true that some low-end models dont allow you to control your focus by hand, well leave that topic for another day.) Our sermon today explains what these three controls do and why you might sometimes want to operate them manually. (NOTE: all camcorders that have manual controls still let you fly on autopilot when you prefer to, and some of these models cost very little more than the auto-only types.) So after a look at white balance, well cover shutter and aperture, and then explain so-called "programmed" controls that combine the functions of both.
The white-balance control matches your cameras color sensing to the overall tint of the light in which youre shooting. Outdoor open shade has a bluish cast, while ordinary light bulbs are reddish. Between the two, direct sunshine is somewhat blue and halogen movie lights are somewhat red. Most fluorescent lights resemble daylight, only they really dont. All clear so far?
The auto white-balance control analyzes the incoming light and guesstimates the best camera setting for pleasing colors, and overall, it works pretty well. But camcorders with switchable indoor, outdoor, and fluorescent settings often work even better.
This is especially true with fluorescents, whose color tint (as the camera sees it) can be markedly affected by the lamp type (cool, warm, or special), the mix of gasses in the tube and even the age of the light fixtures diffuser. (These plastic panels decline over time from milk or clear to a dismal Landlords Tan.) Often the best way to obtain pleasing hues under fluorescents is to switch among white balance settings while eyeballing the effect on a monitor or color viewfinder. Depending on the situation, the outdoor or (occasionally) the indoor setting may work better than the fluorescent position.
As your proficiency grows, you can also use switchable white balance to fool the camcorder into thinking its night during the day (by using the indoor setting outdoors) or that light bulbs are candles or firelight (by using the outdoor setting indoors). Professional videographers rely on an even more sophisticated control to fine-tune white balance for each shooting situation, but for Getting Starters, a selectable indoor/outdoor/fluorescent control is all you need.
The exposure is the amount of light required to record a single video image or "field." (Two fields make one complete picture or "frame," and North American video displays 30 frames–60 fields–per second.) To form an image, the camcorders chip demands a certain fixed amount of light: too little and the image is dark and indistinct; too much and it flares out to white. Regardless of whether youre shooting in a beatnik cellar club or on the Aspen ski slopes at high noon, the camera insists on a certain precise amount of light–no more, no less.
To deliver the required light in bright and dim environments alike, the camcorders exposure system dictates how much illumination reaches the chip at any moment and the amount of time the chip is given to turn that light into an electronic image. The amount of light is determined by the aperture (the diameter of the path through the lens) and the amount of time is governed by the "shutter" (and well explain the quotes around that word in a moment).
To use the classic analogy, exposing a picture is like filling a bucket with water. The wider the hose (aperture) the faster the water flows. The longer you aim the hose at the bucket (shutter speed) the more time it has to fill. So if you must have exactly one full bucket (one exposure), you might need to aim a skinny hose at it for a minute, say, or a fat one for 10 seconds. Either combination delivers the correct "exposure" to water: one bucketful.
To create the correct exposure to light, aperture and shutter typically work together; but its easier to see how they operate by looking at them separately.
The aperture is, quite simply, a hole behind your lens that admits light. The wider the hole, the more light pours in. The hole, in turn, is created by an iris diaphragm, an assemblage of overlapping plates that move to vary the opening in their center, as you can see from Figure 1.
In a fully automatic camcorder, sensors read the light coming through the lens and continuously vary the aperture so that the correct amount hits the chip, regardless of the light level outside. By weighting the value of light from different parts of the image (the center vs. the borders, the top half vs. the bottom, etc.), camera designers have created auto-exposure systems that work surprisingly well.
But when the center of interest is fairly small in the frame and lighter or darker than the overall scene, the automatic system will optimize exposure for the scene and over- or under-expose the subject. When you pose a dark subject against a light background, the center of interest turns into a silhouette. On the other hand, when you shoot brightly lit performers in front of a dark stage curtain or set, they may be too light and their colors may appear crude and smeary.
To fix the problem of backlighting, the simplest camera control is (natch) "backlight." By enabling it, you open the aperture just a skosh to lighten the dark center of interest. At the very least, your camcorder should have a backlight setting.
But that simple compensation wont help the over-bright stage performers. To tone them down, youll need a variable exposure compensation control. To use it, you dial the aperture more nearly open or closed while inspecting the results on a monitor. (As with white balance, professional cameras have even subtler controls, but these are out of Getting Started territory.)
In normal shooting situations, the camera controls exposure exclusively by changing the aperture–the opening in the "hose." Sometimes, however, it helps to control the amount of time allotted to filling the bucket as well, and that means controlling the camcorders shutter speed.
Earlier, we put quotes around "shutter" because no video camera actually has one. The word is just a metaphor borrowed from the older domain of still and cinematic film cameras.
In film, a plate across the buckets top controls the amount of time allowed for filling each bucket. When its in place, the water cant get through; when its pulled back, the water pours in. Thats how a real shutter regulates the time allowed for light to fall on a frame of film.
In video, the so-called "shutter" is really circuitry that determines how long the camera chip codes an image in electrical currents before it collects, processes, and records the result on tape. Normally, this cycle repeats 60 times per second–once for each video field–so the usual video shutter speed is 1/60th of a second. Typical entry-level camcorders operate at this speed and this speed only.
But shutter speeds can be slower or (more usefully) faster. Some camcorders let you set the shutter speed at anywhere from 1/250th to 1/12000th of a second, or even higher. Why? Mainly to freeze, or at least sharpen up, rapid motion. At the normal 1/60 shutter speed, a golf swing, say, is just a blur. But if you shoot it at 1/2000, youll capture a series of sharp, crisp stills that clearly reveal why you keep slicing the ball into water hazards.
Admittedly, this feature is pretty esoteric (unless youre a golf pro), but variable shutter speed far more often acts in conjunction with variable aperture to create so-called programmed exposure.
Getting with the Programs
Programmed exposure settings adjust both shutter speed and aperture. Why? Because the equation must always stay the same: aperture (hose opening) times shutter speed (filling time) equals exposure (one bucketful). Reduce the aperture and you must increase exposure time to compensate–or vice-versa.
That is how programmed exposure settings work:
- The "portrait" setting opens the aperture while increasing the shutter speed to compensate. The wider lens aperture softens the background so it doesnt distract from the subject.
- The "sports" setting is similar, except that it substantially increases shutter speed in order to sharpen fast movement, while widening the aperture to compensate for the shorter exposure time.
Some camcorders include other programmed exposures as well, all of them juggling aperture and shutter speed to produce the same bucketful regardless of circumstances.
Whats the bottom line? Can you shoot pleasing video without manual white-balance, aperture, shutter-speed and focus controls? Of course you can. So if you own a fully automatic camcorder, dont take it out and shoot it. On the other hand, if youre in the market for a new model, these controls are the first essential steps toward letting you control the camera, instead of the other way around.