April 23, 2009 by admin
Lighting used in video capture depends on a variety of factors. These include the limitation for practical reasons and the necessity to use lighting.
First, a brief discussion of what lighting does for video imaging is presented. Any imaging system requires a minimum amount of light to produce optimum results including the human eye. Optimum results are usually interpreted to mean vibrant colors and fine detail of the image. When some of that minimum light is discarded, the colors begin to fade while fine detail is still present. Taking away still more light, the imaging electronics begin to compensate by amplifying (increasing the video gain) of the light that it is working with. Increasing the gain a slight amount is usually not noticeable in the results although significantly increased gain will result in graininess or loss of some minor fine detail in the image.
I would identify four different grades of available light:
- Excellent: colors will be vibrant and pop, detail will be optimum. Usually this is only attainable indoors with auxiliary lighting or outdoors without.
- Good: colors will look very nice with fine detail. This is usually attainable indoors with no auxiliary lighting.
- Poor: colors will be bland and video gain may increase slightly.
- Insufficient: camera gain will max out causing noticeable graininess in the image. Usually halving the shutter speed improves these results dramatically while the resulting motion blur is almost imperceptible. Tight zooms are prohibited.
The Practical Limitation Preventing use of Auxiliary Lighting
There are times when it is not practical to use portable studio lighting such as at a wedding ceremony. This is not only because it would be a distraction but because the distances usually involved between the camcorder and subjects are large making any supplemental lighting ineffective. Fortunately, most sanctuaries have sufficient ambient light for good imaging as defined by the category “good” above.
We do, however, routinely use on-camera lighting at wedding receptions. Please ask to see samples showing how vibrant colors become in even dimly lit dance floors.
Here is a curious note: Some sanctuaries have large sky lights letting in a flood of exterior lighting. When this lighting mixes with the indoor ceiling lighting, a color mis-match occurs which is MURDER for video imaging. The temperature of outdoor lighting is 5700K while indoor lighting is 3200K. Video imaging can deal with one or the other but not both simultaneously. The usual solution for these cases is to have the site manager turn off the indoor lighting even though it gives us less light to work with.
The Necessity to use Auxiliary Lighting
There also times when it would be foolish not to use studio lighting such at a studio interview. Still, there are other times when acceptable results are possible without lighting but the client wants stunning imaging. What it really comes down to is a trade-off between operational conditions and what level of results are required.