Posted 29 September 2005 - 03:01 PM
What are the general characteristics of the television signal and viewing experience that guide on-set lighting decisions (i.e, contrast difference between viewing SD television and 35mm in a theater.)
Thank you in advance for any responses.
Posted 30 September 2005 - 06:13 PM
Introduction to Lighting
by: Chris Cooke
Most people take light for granted. It's a part of everyday life that's so familiar to us that we don't even think about it. Why then is there so much discussion and mystique about lighting techniques? Couldn't we just take one big light, flood a scene with it and leave it as is? Then the talent would be illuminated, and really, all that most people care about is what the talent is saying right?
A lot of beginners who are asked to light a scene have these thoughts run through their minds. The thing is that the talent is what we want people to focus on and think about, not the lighting. The paradox is that this is precisely why great lighting is important. We as lighting directors, cinematographers, gaffers and lighting camera operators have the responsibility of making the talent and sets look beautiful and helping to focus the eye of the viewer on whatever we want them to look at (usually the talent but not always).
It then becomes somewhat puzzling when a straightforward interview needs a dozen lamps, but you find out that a particularly impressive lighting effect was achieved with just a single lamp.
What is the purpose of lighting?
2.Making a 2D image apear to be 3D (seperation and contrast)
3.Creating a mood (depth of field, quality of light, color, etc)
Learning to Light
When lighting for the camera, there are three broad approaches we can follow.
1.Trial and error. Some setups might look great and others will look horrible.
2.Routines. Consistent but somewhat boring lighting.
3.Creative Analysis. We make decisions methodically, based on a real appreciation of how light behaves. Some things to consider are how light modifies and enhances; how it alters the appearance of subjects; how it can develop a mood. We will discover how to manipulate light; how to use light creatively to achieve exactly the effects we are seeking. When problems arise, creative analysis enables us to discover and correct them systematically.
Light travels through space in the form of electromagnetic radiation at over 186 000 miles a second. We measure color in wavelengths (nanometers). When dealing with nanometers, the primary colors for NTSC (National Television System Committee) television systems are specified as red = 610 nm; green = 535 nm; blue = 470 nm. We measure color tempurature in degrees kelvin. Tungsten balanced light (studio lighting) is supposed to be exactly 3200 degrees kelvin (3200k). Outdoor light on a sunny day from roughly 10:00am to 4:00pm is about 5600k. As light becomes warmer (closer to the orange end of the spectrum), the degrees in kelvin decreases.
White light contains all colors of the visible spectrum. Combining the primary red, green and blue colors will produce white light. Also, when a narrow beam of white light is interrupted by a prism, its component colors become refracted to differing degrees, and spread in a spectral band (creating a rainbow).
Light intensity (quantity) is measured with a light meter in foot candles (North America) or lux (metric). A footcandle is defined as a unit of illumination equal to the intensity of one candle at a distance of one foot. Foodcandles are usually used as a measure of light received as opposed to light output.
Quality of Light
The quality of the light directly affects the mood in a scene or on a set. Typically, women are lit with soft light because it helps hide wrinkles and gets rid of ugly nose or chin shadows. I always use very soft light for my fill light(s) and a little harder light for my key. Hard light can be effective, especially when placing shadows on backgrounds. Faces can also look good with hard light but shadow placement becomes very critical.
Methods of creating soft light:
Bounced lighting: This can be done with a specular bounce board such as tinfoil or a soft board such as foam core. Ceilings and walls also work great when on location.
Diffusion Media: There are many different types and weights of diffusion, but its main purpose is to scatter light so that it wraps around the subject.
Softlights: A softlight is a permanent or portable lighting unit that is bounced and diffused. The advantage of softlights over bounced lighting is convenience - you can use softlights anywhere, with no need for a wall, ceiling or bounce board ? and control; it's easier to direct the light exactly where you want it. However, softlights can take up more space.
Relative Distance to Subject: A typically hard source like a Zenon can essentially end up quite soft without any diffusion by placing the light extremely close to the subject. The closer we place a source to a subject, the softer the light will appear. This is why large diffusion frames that are filled evenly with light are often placed right outside the frame especially on closeups.
There are many ways of shaping light to go exactly where we want it to. We use grip equipment to help us do this. Barndoors, snoots, flags, cutters and scrims are just some of the grip equipment available to us. I often use flags or barndoors to build up contrast on a set or get rid of the notorious double and triple shadows.
Some of the fixtures used to shape light in different ways are:
Leko (ellipsoidal) - Outputs a very narrow beam for hilights, patterns and spotlights. Lekos have shutters in them so that we can place the light even more accurately. Gobos are metal disks that can be dropped into a leko for different patterns and effects.
Fresnel - The Fresnel (pronounced fra-nell) lens in the front of the light (named for the person who devised it) consists of concentric circles that both concentrate and slightly diffuse the light. The quality of the resulting light is relatively hard but the lens takes the edge away making the light a little more flattering to faces.
Scoops and Broads ? Open face fixtures that spread the beam over a broad area. These lights are typically softer than fresnels but have shorter throw distances. They are often used for fill and general washes of light.
PAR can - PAR is an acronym for parabolic aluminized reflector. It is perhaps the most widely used light for concerts, nightclubs and touring productions. PARs can be helpful to us when low wattage and high output lights are needed. They are lightweight and come in a variety of sizes and styles (narrow spot, medium flood, wide flood).
As a rule, the most attractive lighting occurs when using an approach called three point lighting. This is not by any means a hard set rule but it's definately a good starting point.
Key Light ? The key light is the primary source of illumination. It is usually positioned off to one side of the camera and tilted down at the talent at a 45 degree angle. This key light:
Establishes light direction.
Creates the principal shadows.
Reveals form, surface formation, and texture.
Largely determines the exposure.
Fill Light ? This light is used to fill shadows without causing a shadow of its own. The amount of fill in a scene or on a set directly impacts the mood and visual interest. Too little of fill and we won't be able to see into the shadows (not necessarily a bad thing, especially when lighting a moody, highly stylized scene). Too much fill and the scene becomes flat and boring. The best place to position your fill in most cases is just above eye level and right beside the camera (opposite the key side). The fill light should be soft and usually (but not always) warm.
Back Light - The back light is important in creating the illusion of depth. Television and film are two dimensional formats and one of our main jobs is to make nearly everything we shoot look three dimensional. Depth is the dimension that is missing from a 2D image. Back light is one of the ways in which we create that three dimensional look.
Placement of the back light is critical depending on what you want it to do. Kickers, rim lights and hair lights are all forms of back light.
The typical lighting ratio of key light to back light is 2:1, but that's not a rule that you have to stick to. A back light can actually turn into the key light if you want it to. Remember the definition of key light? It's the primary source of illumination. For instance, if you are doing a scene outside with a woman who's face you want to flatter, it can be beautiful to backlight her with the sun and then bounce sunlight onto her face or use an HMI (halogen metal iodide) as a soft fill and then expose for her face. Even though the sun is the back light, it's also the key light. This setup is often used in beer commercials or glamor photography. My biggest caution with this is that you give the talent enough fill so that the back light does not overexpose.
Eye Light (a.k.a. catch light) ? An eye light can be the extra touch that a scene needs to bring out life in the talent. The fill or key light often doubles as an eye light (depending on positioning) but there are times when you need to put a light up specifically for this purpose.
Background Light(s) ? Background lights are used to bring out interesting details in the background or help make the scene look more interesting. My main use of background lights usually has to do with contrast. Without highlights in the frame, you will probably get a flat picture. Just as uninteresting though, is a background that is over-lit. When the whole background is evenly illuminated and/or brighter than the talent, it can be very uninteresting and even distracting.
Practicals ? The term ?practical? refers to any unit on set that needs to be electrified, whether it is considered scenery, props, or costumes. Practicals can be a source of motivation for bigger lights outside the frame, or they can just add visual appeal in balancing the frame.
Gels and Diffusion ? The color and quality of the light can be manipulated by gels and diffusion. The way that color makes us feel and perceive is amazing. Color is a world of its own that we won't get into right now.
There are also many different types of diffusion. They all spread light in different ways. Its basic function is to scatter light so that it appears soft.
By now, it's quite obvious that lighting is both an art and a science. For a more experienced lighting director, the emphasis begins to be put on art because he/she no longer has to think about the technical side that becomes routine. There is very little artistic or technical information in this basic guide compared to what is out there for you to learn. If you are at all interested in the amazing world we can create with light, please take it upon yourself to learn all that you can with books, online forums, practical application and asking questions.
Posted 30 September 2005 - 06:35 PM
Most of the technical considerations will either be worked out through testing and or relying on past experience. When shooting HD, a properly calibrated monitor and camera can allow you to make judgment calls on contrast and exposure by trusting what you see on screen is being recorded to tape.
With film, one knows the stock they are shooting, and what happens to it through the telecine process.
So the bigger picture as far as what affects the look of a show is time. In a situation with a longer schedule, there is opportunity to fine tune the lighting more from setup to setup. Sometimes you find yourself thinking about adding a light, but decide you just don't have the time for "extra credit", so you hand off the set knowing you had to compromise.
You are always faced with compromise, just the less time you have, the more you have to compromise.