Camera Operation
Manual vs. AutomaticMost consumer/prosumer digital video cameras offer fully automatic operation of all camera settings. Prosumer cameras will also usually offer manual control over all settings, and consumer cameras may or may not offer manual control over some or all camera settings. The better (usually more expensive) your camera is, the more manual control you will have over it.
The cameras' automatic systems generally work by comparing the current image information with preset "avarage" scene data, then adjusting the settings until the current image matches the average scene. This basically results in average video.
Home videos are usually shot using the automatic controls. This means that if you use the automatic controls, your video will look like a home video.
In general, when trying to create professional quality video, you should always use the manual controls on your camera.
By using the manual controls, you are able to tailor each individual setting to your particular scene, ensuring that you get the best possible image for that scene. You also are able to "lock" specific settings in, so that they don't change every time something in the scene changes.
There are occasions when it may be neccessary to use the automatic controls. For instance:
- In a documentary or news setting where events are occuring so fast that you may miss them if are messing with your camera settings all the time.
- In a situation where you have little or no control over the subject or environment (lights, movement, etc)
- In a situation where you cannot directly view your scene through the camera's viewfinder or on a monitor (hidden cameras, camera is mounted on a pole or vehicle, held overhead, etc).
Focus
When an image is in focus, it is sharp and detailed; when it is out of focus, it appears soft and blurry.
Usually you want the most important element of your scene in focus.
On autofocus, the camera must guess what to focus on. Because it doesn't know what part of the image is most important, it will usually focus on whatever is in the center of the frame, or on the largest object in the frame. Often, this is not what you want to focus on. Additionally, if the camera or subject is moving, autofocus will attempt to constantly refocus to keep up with the changing scene. As this happens, the image may quickly snap in and out of focus. If the camera cannot find something to focus on it may continue to adjust itself, or "hunt", for the correct focus. This will be very obvious to your viewers, is very annoying, and it can easily ruin an otherwise perfect video.
It can be difficult to achieve perfect focus using the small, low resolution viewfinders and LCD screens on most MiniDV cameras. Whenever possible, you should use an external television or monitor to check your focus.
Some cameras have a "push auto" button which will temporarily switch on autofocus, usually until you release the button. This can be useful if you do not have an external monitor to check focus on. With the camera on manual focus, center your subject, hit the "push auto" button, let it focus on your subject, then release the button and recompose your scene. This way you let the autofocus work for you, but then lock it down so it doesn't start to "hunt" if the scene changes slightly.
Iris/Exposure
The "iris" or exposure setting on your camera lets you adjust how bright the image is.
In digital video, when any pixel in your image hits 100% brightness, it is essentially pure white - there is no more room for image information. In general, you want to adjust your iris control so that everything is below 100% pure white except for highlights (such as the sun glinting off of chrome). This way you maintain image detail even in the brightest portions of the image...a white shirt, for instance, will still show the texture of the cloth.
Some prosumer and most professional cameras have a "zebra stripe" setting. Zebra stripes are diagonal lines which appear in your viewfinder over portions of the image which have hit 100% white. You can use them as a guide, adjusting your iris control until almost all the zebras are gone.
Once you have adjusted your iris for the brightest parts of the image, you may find that other parts of the image become too dark. In that case you should use lights and/or reflectors to brighten up the darker areas in the image and balance your exposure.
Shutter Speed
On film cameras, a shutter opens and allows light to strike the film, thereby exposing the film and recording an image. By varying the length of time the shutter is open you can allow more or less light to reach the film, which determines how bright the recorded image is. Shutter speed is the measurement of how long the shutter is left open, expressed in fractions of a second. Common speeds include 1/4, 1/8, 1/32, 1/60, 1/150, up to 1/10,000 or higher.
On video cameras, the same effect is achieved electronically by varying the length of time the signal from the CCD is sampled. Although there is no physical shutter, this is still referred to as shutter speed. The default speed on most video cameras is approximately 1/60 sec.
The slower the shutter speed, the longer the period of time which is recorded in each frame. If your subject is moving quickly it will appear blurry in individual frames. This effect is called "Motion Blur".
The higher your shutter speed, the less motion blur you get, while lower shutter speeds produce more blur. Some motion blur is usually good; the viewer is not conscious of the blur, but motion will appear smoother on screen. Too much motion blur makes the blur obvious to the viewer, which in some cases may be desired and used as an effect. With higher shutter speeds the image will be much sharper, which can be useful when extracting still images from your video. However, this generally does not look natural when watching the video, but again, it may be a desired effect.
In general, you will want to lock your shutter speed in at about 1/60 for the most natural looking image, because this approximates the human eye's level of motion blur. In extreme lighting situations you may need to use a higher or lower shutter speed in order to compensate for too much or too little light, but be aware that the image may look odd to your audience. Additionally, very high or low shutter speeds can result in interesting effects which may change the mood of your scene; you should experiment with and become familiar with these looks so that you can determine when and if you want to use them.
White Balance
Different light sources will give off different colors of light, and it is important to calibrate your camera to the particular lights in a scene.
Light color is expressed as a function of temperature, measured in degrees kelvin. Sunlight is approximately 5600k, while incandescent (indoor) lights are around 3200K. The higher the color temperature, the bluer a light is, and the lower the temperature, the redder it becomes. Sunlight has a very blue color, while indoor lights are somewhat yellow.
Manual white balance lets you adjust your camera to your primary lights. If you do not white balance your camera, your video will have a color cast to it. If you let the camera balance itself, and you have several different colors of light in your scene, the color of the scene will shift as the camera tries to compensate for the different lights.
To set your manual white balance you will need a sheet of white paper or a white shirt. Place the white object so that it is evenly lit from your primary light source. Point the camera at the object, and zoom in until all you can see is white. Now hit the white balance button, and the camera will adjust itself so that the paper appears white.
Many cameras have preset indoor and outdoor white balance settings. In many cases these will work, because unlike auto white balance they do not change once they are set. However, they will not exactly match your lighting, so if you have the time you should always try to balance manually.
Zoom
Every camera you can buy now has a zoom lens. This lets you frame your subject tightly from various distances, and usually has an optical magnification factor of 10-20x.
Many digital cameras have "digital zoom" settings which go up to 100x or higher. Instead of using the lens to zoom in, they actually enlarge the pixels electronically. Unfortunately, the more you enlarge the pixels, the less resolution you have, and the worse your image will look. You should not use this setting...if you need to zoom in more than the lens allows, pick up the camera and walk closer to your subject.
The zoom should be used to change the composition of your shot before you begin to record, not during recording. There is no equivalent to zooming in the human eye, so when you zoom it tends to draw attention to the camera rather than the subject. Additionally, the proliferation of zoom lenses on camcorders has led to the zoom being particularly associated with home movies. Once again, avoid the zoom if you don't want your videos to look like home movies.