Multiple Lights

Multi Light Usage

Using more than one light for studio work involves placing the lights in relationship not only to the subject, but to each other as well. The relationship of lights not only depends on the physical placement, but also the power output, modifiers used, temperature of light, and more interactions than could be covered in several books. For the purpose of this class, we will be working with lights of the same temperature and dealing primarily with power, placement and modifiers.

How Does Light Work

The main thing to remember when using multiple lights (single light as well) is how light works. Light can only travel in a straight line. It does not bend. Light can be redirected easily though. Light can be filtered for a specific color; once this is done it cannot be undone. Light is made up of countless individual rays of light that cannot be seen individually by us, only as a whole. Light is not a big solid beam, but can be made to look that way.
The difference between direct light and diffused light is not a softening of the light; light cannot be softened, only redirected. What we call soft or diffused light is actually light that has been scattered. The light is still traveling in a straight line, but there are now countless rays being directed in every angle imaginable instead of in a more direct path. This randomness of light paths is what fills in areas more evenly and appears to wrap itself around a subject. It reality it isn’t, the extreme range of angles the light is now traveling in has a much better chance of hitting the subject in different places. The further you travel away from a diffused light source, the more it will become a point light source and the more a shadow will become apparent.
Using modifiers to redirect light (reflectors, diffusers, gobos, barn doors, grinds, snoots etc…)
Keep this all in mind when placing your lights. Straight line of light will determine shadow direction and diffusion of light source combined with proximity will determine shadow intensity.

Lighting Ratios

Lighting ratios are the main concern when working with two or more lights. The term refers to the ratio of light being put out by one source in relation to another. The ratio is always referred to with the first number being the main (usually the most powerful) light and the second being the fill. The main will always be the number “1” in the equation and the second number being how many stops less +1 the other light is putting out that is reaching the subject. So, a 1:2 ratio will have the main light at full with the fill light having 1 less stop or ½ the power so 1+ 1 (stop less) will give you the 2 in 1:2.
The ratio does not have anything to do with actual power being output from the source. It has to do with the amount of light making it to the subject. Two lights set at the same output levels, but at different distances away from the subject will not have a 1:1 ratio even though they’re putting out the same amount of power. The same applies to lights using different modifiers that can affect the amount of light hitting the subject.
The exception to the rule is if you see a ratio that says something like 3:1. The number 1 still refers to the main light, which is what you are metering for, but the higher first number refers to a light that is being used to overexpose an area. An example would be for a high key shot where you need to ever expose the background in order to blow it out for effect. The stronger lights would then pointed directly at the background, pulling the subject further out to avoid spillover onto the subject from the background lights and allowing the exposure from the main to be unaffected.

Categories of Lights

Main: The main light is just that, it’s the light that produces the light that is used for the exposure of the subject and is the one that is metered for exposure value. It is not always the most powerful light being used. It is always the light that produces the exposure value that will be set on the camera.

Fill: The fill light is the light (or lights) that is used to fill in an area on the subject that is in need of extra light hitting it. This normally means the shadow area opposite from the main, but not always. The fill might also be from a shorter angle to add to the main or from the side to fill more along the edge. The fill will always be a smaller exposure value than the main.

Hair Light: The hair light is hung above the subject and is used to create a smooth highlight along the edge of the hair to give it more separation from the background. The angle it is set in relation to the subject will determine the amount of highlight created. An angle from further back will have a thinner line, straight above will produce a broader line and in front will light the hair fully, but will also have spill off onto the face most likely. You can use a snoot to direct the hair light more accurately, but this will also create a more focused highlight and the exposure value will increase.

Kicker: the kicker light is a small powerful light that is directed to a specific area to really boost the exposure value of it. It is usually directed upwards, but can also be straight or downwards also. The kicker light might have (and usually does) a higher exposure value than the main. This is normally used in fashion photography, so use it to get that look. The light from the kicker should be minimal on the area it is hitting on the subject. Do not over power a subject with the kicker.

Background Light: The purpose of the background light is to provide illumination to the background. It is normally placed behind the subject directed up toward the backdrop. This will give a brighter area behind the subject with a falloff to the edges of the image. Altering the angle and distance of the light in relation to the backdrop will give different effects for it. Closer will produce a brighter area behind the subject with a faster falloff; farther away will give you a softer more gradual falloff. When lighting for a high key situation, then the background light will be set at a higher metered value than the main.

Backlight: Do not confuse with background light. A backlight is used to light the subject from behind and is aimed toward the camera, not the background. The effect you would be going for is edge lighting around the subject. This is mostly visible on someone with lots of hair that is thick.

Metering

When metering for multiple lights, first decide which light is to be the main for exposure. Set that light and take a meter reading for it with no other lights on. Now place the fill light, turn off the main and meter for it. The meter reading should be less than it was for the main. How much less is determined by what the final image result you want is.
If you’re using a back ground light, place it and again meter from the spot that will be centered in the image toward the camera. It should be over, under, or the same as the main all-depending on what the look you are going for is.
If using a kicker…. Turn off the other lights and now meter the kicker as placed in relation to the subject, meter toward the spot where the kicker will hit. It should be slightly over the reading for the main light. How much over is again determined by the effect you are looking for.
Using a Backlight…Meter the light as if the camera will be directly behind the light instead of being in front of the subject who is in front of the light. So, meter toward the background. The reason is to get an accurate measure of the light that will be illuminating the edges of your subject. Light should be over the main if you want a hard “electrical” halo effect. Less if you want a slight differential from the background that is not overpowering.