Module 31

    

Updated: 01/02/2014

 module 31

  

 

The Key

Light

 

 

 

" It's impossible to make an actor or set look good from three opposing angles at once unless it's lit like a WalMart."

 --Robert McLachlan, Cinematographer, Bionic Woman, 2007

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>> In typical lighting setups, lighting instruments serve four functions:

  • key lights
  • fill lights
  • back lights
  • background lights

The photo below was shot with so-called formula or 3-point lighting effectthree-point lighting.

Even though some lighting directors say there is no such thing as a "formula" for lighting, the formula we'll discuss will provide excellent results for most of your ▲ video work.

We'll have a series of examples that shows this formula in action.

If you study this photo you may detect four light sources:

  • one on the left (the key light )
     
  • one of the right (a much dimmer fill light )
     
  • one on the hair (a back light ),
    and
     
  • one on the background (a background light

    Note: black and white photos and movies are often preferred when studying lighting because lighting effects are more readily apparent without the dimension of color.

    By the way, in case you are wondering, we call this three-point lighting, even though it involves four lights. Since the background light is not on the subject, it doesn't count in three-point lighting.

The combination effect of these four lights (put in exactly the right place, at exactly the right intensity and with the right quality/coherence), creates an optimum over-all effect.

We'll start with the key light in this module and take up the other lights later.   

Key Light Considerations

As the name implies, the key light is the main light.

" The key light highlights the form, dimension and surface detail of subject matter."

In terms of coherence or quality the key light should be in the middle of the hard-to-soft range.

As you can see from some of the illustrations in these chapters, light that is either too hard or too soft is not desirable for most subject matter -- especially people. This middle ground between hard and soft light is often achieved with a Fresnel light.

key lightIn three-point (formula) lighting the key light is placed at an angle of between 30- and 45-degrees from either the left or the right of the camera.

In the photograph of ▲ the model at the start of the module the key light is on the left, just as it's shown in this drawing.

Forty-five degrees off to one side is best because, among other things, it brings out optimum texture and form (dimension) in the subject. For the sake of consistency, the 45-degree angle will be used throughout this discussion.

This brings us to the rule we'll need to keep in mind, especially if multiple cameras and camera angles are involved in the production:


Light for the close-up camera.


In multiple-camera dramatic productions you will have to confer with the director during the camera-blocking phase of preproduction to find out which cameras will be taking most of the close-ups of each person.

Does it matter if the key is on the right or the left? Possibly.

There are four things you need to think about in making this decision.

  • follow source Is there an apparent source of light in the setting such as a window or nearby table lamp? If so, be sure to key from this direction.
     
  • consistency In most settings it will look a bit strange if two people are sitting next to each other and one is keyed from the left and one from the right.

  • the person's best side Put the key on this side. It will emphasize the positive and downplay the negative facial characteristics.

  • what's most practical If there is a wall or obstruction on one side of the subject -- a possible problem when doing on-location shoots -- you will generally want to key from the side that will enable you to use a 45-degree angle.

One thing you don't want is to "put lights everywhere" in a frantic effort to wipe out every shadow from every conceivable camera angle. 

Controlled shadows give subjects desirable form and dimension, and the illusion of three dimensions.

At the same time, it's sometimes necessary to sacrifice form and dimension to cover multiple camera angles.

" In typical studio and on-location news programming the best lighting effect is often sacrificed in favor of rather flat, shadowless lighting, which is simpler, less demanding, and holds up over more camera angles."

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It's not unusual for a large set in a major dramatic setting to require more than 100 lights -- but they are grouped to best light specific talent areas.

Often marks are put on the floor to indicate where talent should stand. Stopping at one of these indicators is referred to as "hitting your mark."

Unless basic lighting simplicity is preserved for these close-up talent positions, things can end up in a mess, which brings us to another lighting guideline:


The simpler the design, the better the effect.


Among other things, the key light creates a catchlight in the eyes of subjects -- a (single) spectral reflection in each eye that gives the eyes their "sparkle." In the ▲ eyes of the model previously shown notice the single catchlight in the eyes.

When you "put lights everywhere," it not only results in a multitude of catchlights in the  eyes, but it generally results in flat, lifeless lighting.

Numerous lights hitting talent areas also create a confusing horde of shadows. Barn doors and flags can be a great help in keeping light out of unwanted areas.

The Key's Vertical Angle

>>We have established that the horizontal angle for the key light is approximately 45-degrees to the left or right of the subject in relation to the camera. One other key light angle should be considered: elevation.

As shown below, this angle is also commonly 45 degrees for the key light. We'll cover the other lights shown later.

3-point lighting

Some lighting directors prefer to place the key right next to the camera, or at a vertical angle of less than 30 degrees. Sometimes in limited on-location conditions this may be unavoidable.

However, three problems result from reducing these angles:

  • the full illusion of depth and form will be sacrificed (not especially desirable unless you want to create a flat effect with minimal surface detail)
     
  • there is a risk of having shadows from the key light appear on the background directly behind the subject (where they are most objectionable)
     
  • the talent is forced to look almost directly into a bright key light when they try to look at their camera, which can result in squinting, not to mention make reading a camera prompter difficult

Ideally, when the talent face their close-up camera they should see the key light 45-degrees off to one side of the camera at an elevation of about 45 degrees -- which is not unlike the effect we often see outside in sunlight.

heading

In recent years there has been a move to flatter, softer lighting in non-dramatic productions. This gives on-air talent a more youthful appearance, is less demanding in terms of lighting expertise, and it allows the use of multiple camera angles without the fear of shadows.

But, as you can see in the photos below, flat lighting (on the left) comes at the expense of form and perceived dimension (on the right).

soft light example formula lighting effect

>>Even so, as we've mentioned, some lighting directors feel that relatively flat lighting has advantages for news and interviews. LED Key Lights


A commonly used lighting setup for this is shown on the left.

Note that color-balanced fluorescent or LED  light banks are used for keys.  Although no fill light is needed, the use of  backlights behind the subjects is recommended. 

Because of the soft, diffused key lights, a background light may not be necessary. More on these lights a bit later.
 

Keys and Boom Mics

>>Returning to our formula approach to lighting, since the key light -- typically a Fresnel -- is the brightest light on the front of a subject, it's the one that will create the darkest shadows.

Shadows from boom mics (microphones suspended from long poles over the talent areas) can be minimized by positioning the boom parallel to (directly under) key lights.

By not placing talent too close to a background, the boom shadow will end up on the floor rather than creating distracting shadows on the background -- assuming you keep the key at the recommended height of 45 degrees. 

 

The Sun As a Key

>>When shooting on location during the day, the sun will normally be your key light. However, direct sunlight from a clear sky results in deep, black shadow areas with a major loss of detail.

If the sun is directly overhead, a "high-noon effect" will be created, producing dark eye shadows. Put technically, in both instances you've grossly exceeded the contrast or brightness range of the video system.

Suffice it to say, direct sunlight, especially for close-ups, can look unflattering, not only to the person in front of the camera, but for your mastery of production skills.

To get around the "high noon effect," it may be best to shoot sunlit, on-location productions in mid-morning or mid-afternoon when the sun is at an elevation of about 45 degrees. If this is not possible, you will need to consider a fill light, which will be discussed in the next module.

>>On an overcast day the diffused sunlight will provide a soft source of light.

If the diffused sunlight is coming from behind thesoft lighting effect  subject, it can provide good back lighting, while the ambient light from the overcast sky furnishes soft front lighting.

With the proper level of cloud cover this can result in soft, flattering lighting, as shown in this illustration.

But there can be a problem.

Note the bright background in this photo. In camcorders with automatic exposure control this will result in underexposure (with unnaturally dark skin tones) unless the back light control is used to open up the iris two or three f-stops.

If the camera has a manual iris control, you have an even better option.  You can manually open the iris while carefully observing the result in the griffolyn screenviewfinder.  (Recall that the module on quality control discussed this concept.) 

The soft light effect in direct sunlight can be achieved with the help of a large translucent screen.

 A thin white sheet can sometimes be used, but for professional applications commercial versions, such as this Griffolyn screen, are available. Although this setting is in harsh, direct sunlight, the subjects sitting in the Jeep are softly lit.




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