|
In the studio the photographer can use a strobe to control the light falling on a subject. Most studio light sets have a bright strobe that reflects off of a white umbrella to direct light onto the subject in a softer look. Light directly from a strobe comes in a straight line and makes harsh, hard shadows on the subjec. The umbrella softens the light and makes it come from a wider angle on the subject creating softer shadows. We call this directional diffuse light which makes the best type of light for getting natural skin tones.
 Three lights are used for studio lighting. The first light is the brightest and is called the key light or main light. It often is set to come from above and slightly to the side of the subject much like we would want the sun outdoors. The second light is called the fill light. This light represents reflected light that would fall on a subject outdoors. The fill light softens the shadows by slightly filling them in while lightening up the dark side of the subject. The fill light is almost always less bright than the main light and is placed on the opposite side of the camera than the key light and is usually not as high. Some photographers put the fill right next to the camera. The third light in the set for the studio is the background light. It is usually placed directly behind the subject aimed at the background and is used to eliminate shadows from the subject that might fall on the background. A fourth light might be added which is called a rim light or hair light. This light is behind the subject and slightly higher than the other lights. It provides a glow or halo around the subject and helps separate it from the background. In some cases only the MAIN and FILL lights are used as they are the most important. Some photographers will add a reflector that takes the place of the fill light in adding light to the shadow side.
In the studio light falling on the subject may come from both the key light and the fill light making exposure calculation from the strobe using mathematics difficult. The umbrella also softens the light and spreads it out over a wider area reducing the brightness. To calculate the exposure in such a case a photographer must use a special meter designed to record the burst of light seen from a strobe. These will give you the aperture to use. They can also be used to adjust the amount of light from the FILL to be one f-stop less than the main light.
SLAVE STROBE
When more than one strobe is used in the studio a problem with electrical wiring of the strobe to the camera can be cured with a slave. This is a special strobe that has an electronic sensor that sees a burst of light from another strobe which turns on a trigger for the slave strobe. Thus the slave fires around 1/10,000 of a second behind or after the main strobe, but is not visible to either the human eye or the film. Both appear to fire together. Because the slave is looking at a burst of light that is brighter than the room light it is important that the senor NOT be aimed at the sun or some other source of bright light for it to work properly. In addition it must have a line of sight vision of the main strobe. To solve this lighting problem the pro will use a radio slave set up that has a radio transmitter that is placed in the wire connection between the camera and strobe that is used to trigger a radio receiver on the slave strobe. This can work over a greater distance such as indoors in a gymnasium for a sports photographer.
The fill flash is used outdoors when our subject has a very bright background or when it has shadows on it that are distracting. The flash is used much like a reflector might be used to shine additional light onto the subject. The diagram labeled "Display Fill Flash 2" will show the set up that was discussed in class.
The flash is difficult to use outside in bright sunlight because of the need to set the shutter speed on the camera to syncronize with the strobe. This shutter speed on lower priced cameras is around 1/60 of a second. On a higher priced camera it goes up to 1/250 which allows for better exposure possibilities.
FILL FLASH
 To use the flash for a fill we must set our exposure meter by first setting the shutter to 1/60 (the sync speed for the flash) and then reading the bright background behind our subject. This is likely to be very bright and give us an aperture of about f16 or f22. We then plug that information into our formula where X = GN/f stop to give us X = 100 / 22 thus X = 4.5 feet. This tells us that for the flash to have light that is EQUAL to the background we must stand 4.5 feet away from the subject. If we want the light falling on the subject to be less we would change the aperture in the formula from 22 to f16 for a new distance of 6 feet and so on.
The fill flash is used by most professionals and is what adds that extra touch to a quality photograph. A slave strobe can be hand held by an assistant or a reflector can also be held up to add a third light source to a set up and make the shadows on a persons face look even better.
In the movie industry a fill light is used or a reflector is used to allow the light inside a building to equal the light outside the window so that the exposures are identical. IF they were not the same then the window would be overexposed and look white. Thus actors must work under very bright lights when they are indoors if the scene is to show something visible in the window.
|
