First of all, speed is important. Time on d the set costs money, even on the smallest production. Beyond that, you must consider get- and underexposure. Exposure is always important, but in HD must maintain editorial continuity. What are the requirements? What tools do you have? What are the opportunities? What Are the Requirements? This one may seem too obvious to think about, but it is surprising how often it gets lost in the process. Here are the requirements you need to consider: 1.
What is the look that you and the director have decided to go for on the whole project? What is the dramatic intention of the scene: to shock, to make the audience laugh, to frighten them?
Here are some other questions you want to ask: 1. Is it interior or exterior, a combination of both? What time of day is it in the scene? Where does the action within the scene take place? How many people in the scene? Do they move around? Do we see the ceiling? Are there any practical effects—such as turning on a light? Do you need to establish lighting continuity for future scenes, cutaways, or product shots?
What is the slowest lens usually the zoom you might use? Any high-speed or macro work? What Tools Do You Have? What you plan to do with a scene is ultimately shaped by what tools you have available. What you can do with a ton lighting truck is substantially different from what you can do with a minimal lighting kit. This is not to say that what you do with a few small lights is going to be worse than what you do with a large array of gear; it just means you have to plan things differently.
What gels and diffusion do you have? Do you have some practical bulbs? How much grip equipment is available? What size crew do you have? What is their level of experience? How tight is the schedule? Except when you have a generator on the job, the limiting factor is often how much power is available. Lacking a generator, you are most often limited to what you can plug into the wall. In many cases, there might be only a few amp household circuits you can get to.
If there is already some large appli- ance such as a refrigerator on that line, then what you can plug in is very limited and keep in mind that the refrigerator might not have been running when you tested the circuit.
Once you can get a genny on the job, you are not necessar- ily home free. Generators are expensive, and the larger they are, the more they cost. When the budget is tight, you might well be limited to a or amp generator or even a 4K putt-putt. This will certainly affect the size and type of units you can run, thus affecting your overall approach to light- ing scenes for the day.
How much time you have is a major consideration. It is determined by the schedule, which is made by the assistant director. Ultimately, you will have X amount of time to accomplish your task.
It takes practice. When you are really on the run, it often pays to have a Plan B and a Plan C. Thus, if the clock simply runs out, you have something you know will at the very least work.
There are dozens of ways to light any particular scene; but where do you start? What Are the Opportunities? It might be the windows, or a desk lamp, or even a large palm you can hide something behind.
It might be an existing streetlight that you can imitate by hanging something from the pole. This survey of the opportunities will most likely happen during the location scout as you walk around with the director and your gaffer.
In the case of a built set, it might occur in conferences with the production designer or while looking at the drawings of set designs.
Having considered your resources in equipment, crew, and time, you have a basic plan. Be careful: a couple of traps are waiting to snare you at this point. Sometimes, on smaller projects, the director will just describe the scene to you and then go off to attend to some- thing else. What usually happens is that you make the set look great, but there is no guarantee that you are properly lit for the action of the actors.
You must insist on seeing a proper rehearsal. It is impera- tive that everyone remember that rehearsals are NOT just for the actors: they are for everyone. They are for the AC, so she can set marks, they are for the DP to judge the lighting, they are for the grip to set any dolly marks, and so on. It is not usually important that the actors go through the scene with full acting intensity.
For you, the focus puller— and for the gaffer, the grip, the sound recordist, the boom operator, etc. The blocking rehearsal is for blocking. The acting rehearsals come later—right before the camera rolls. Insist on a rehearsal! Most of them just come from experience and experimentation. There are, however, some things to keep in mind that will help you through the day. Plan several moves ahead. For example, many DPs insist on having an Inkie with a hand dimmer standing right by the camera in case they need a last-minute eyelight.
Bringing in a ladder to do overhead rigging is time- consuming. These are just a few lights on stands and ready to go, in case you need them for a last-minute scramble or a reset. They should have power available, scrims hanging on the stand, even some precut gels and diffusion with the unit.
But in the end, what is the real hidden secret of the pros? Have a great gaffer and key grip—it makes a huge difference. Lighting Fundamentals Light is what we work with. In order to shape it to our purposes, it is essential to understand the basic jobs it can do for us.
The Basic Elements Key The keylight is the main or predominant light on a subject. Although we gener- ally think of the key as coming from somewhere in the front, there are many variations: side key, side-back key, cross key, and so on. One way of thinking of the key is that it is usually the light that creates a shadow of the subject. There may be a key for the whole scene or a key for each object in it, or any combi- nation of these.
In a moving shot, an actor may have several a keys and move from one to the other. Any light that balances the keylight is referred to as the fill. Fill lights come in many varieties. Although these characterizations may apply for the most simplistic type of formula lighting, they simply are not true in all cases. Backlight c Backlight is any light that comes from behind the subject.
When backlight comes from almost directly overhead and high enough to get over the head and onto the face and nose, it is called a toplight. In most cases, a backlight that is too toppy will be avoided. It is also called a hairlight. A kicker is a light from behind the subject, but enough to the side so that it skims along the side of the face.
Since it is extremely rare that we are willing to let the kicker, and ill. The name is a misnomer as there are actually more than three lights Backlight involved, even in the simplest setups.
An overhead view a and from behind the camera b. A 2K fresnel unit is bounced into a white beadboard above the window to simulate the light from an overcast sky. Its name is derived from the beautiful actress Merle Oberon. It was discovered early in her career that this type of lighting was most complimentary to her facial structure.
Ambient Ambient is just as the name implies, overall ambient. Note also the 2K zip light rigged on the wall on the right. Quality of Light The variations in the quality and mood of lighting are nearly endless. Perform this simple experiment for yourself. For one full day, look around you; everywhere you go examine at the quality of light in the place you are in. Every quality of light that you see can be reproduced on a set or location. Ask yourself, how would I light a scene to achieve this look?
What units would I use, where would I put them, and how would I modify and shape the light to achieve this? The larger the radiating source in relation to the subject, to remember about soft light is that it is the apparent size of the the more the light tends to wrap around the contours of the source relative to the subject that subject. Where a hard light small source would create shad- determines how soft the light is. Hard light is Photo courtesy of Lite Panels, Inc.
It is a function of the relative size of the source, either from a large-bounce source or difusion that makes the source appear larger. A Source Four leko is used for hard light. For the soft light, a 2K with a Chimera softbox is used. What this means is that no light is inherently hard or soft. Even a soft light unit might, under certain conditions, be a hard light, while something we would normally think of as a hard light, such as a bare-lens fresnel light, might be a soft light.
The deciding factors are actual size of the source such as the size of the lens of a fresnel light , the actual size of the subject, and the distance between them.
The major determi- nant of this wrapping is the size of the source relative to the subject. If a very large light source is illuminating a smaller subject, the light will be able to get farther around the curves and edges. Why distance? A studio soft light is soft because the radiating source is the size of the opening. If a subject is 1 foot high and 2 feet away from the light, it is obvious that the source is huge in relation to the subject.
Even with a large source and a small object placed far apart, only the light rays that are traveling parallel to each other reach the object. Any rays that would have the ability to wrap miss the subject; only the parallel rays illuminate it and the result is a relatively hard light. Specular light is light in which the rays are relatively parallel. Light from the sun, a point source 93 million miles away, is specular.
Specular light is highly directional and collimated. Diffuse is a condition where the light rays are traveling in random, disor- ganized directions. Light bounced off a rough white surface is diffuse. Light traveling through thick white translucent material is diffuse. Difusion Materials Traditionally, diffuse light is thought of as soft and specular light is thought of as hard. Diffusion material can be any semitrans- parent or translucent material: white plastic, silk, nylon, bleached or unbleached muslin, or shower curtain.
They all serve the same purposes: 1. They reduce the specularity of the light. Relatively specular collimated light that falls on one side of the diffusion material emerges on the other side more diffuse randomized ; the degree of change b depends on the opacity and thickness of the material.
They increase the size of the radiating source. The size of the source of a fresnel light is the size of its lens. If a inch light illuminates a dense diffusion material 24 inches in diameter, it becomes a inch radiating source; this also makes the light more diffuse and wrapping.
This effect depends on the thickness and density of the material. The thicker c and denser it is, the more the source becomes a pure area of diffuse radiation.
If the diffusion material is very thin and light, the area of diffuse radiation increases, but also direct specular radiation still comes through. Light from a radiating source is highly directional specular. The fresnel lens cannot smoothly combine these two types of light, d and untreated direct light from one of these units is always just a little bit raw.
One reason for this light and with a ill on the shadow is the slow emulsions used at the time; in order to main- side almost seems like soft light. The light is not simply lost, however. It is useful to think about where it goes. Some is bounced back to the back surface of the diffusion and wasted and some is a lost as heat in the diffuser, but most of it is not lost at all; it simply spreads out to cover more area.
After placing diffusion in front of the light, you have only 50 foot-candles, but you now have exposure over a larger area. Natural Difusion Environmental factors also play a role. The greatest diffusion of all, of course, is an overcast day. Slight overcast essentially turns the entire sky into a huge radiating source: the ultimate soft light. Other Qualities of Light Direction Relative to Subject The direction from which the light hits the subject is crucial to the quality of light.
It is perhaps the key determinant of how the light interacts with the shape and texture of the subject. Altitude The height of the unit in relation to the subject is also criti- cal.
It is another aspect of direction. As a broad generaliza- e tion, lights that are higher are going to create more shadows, and hence more shape. Of course, as with all generalizations, this one is not quite true; we cannot say that it is always better to move a light higher or lower; however, it is fair to say this is usually the case. Historically, comedies, household, product commercials, d and other light hearted material is lit high-key while myster- ies, romance, and stylish upscale commercials tend to be low-key.
It originates at a source and follows a fairly straight path. Specular hard light just outside the frame will usually be sourcey. Soft light, such as bounce light or highly diffused light, will tend not to be sourcey. Highly diffuse light that covers all of the set is called ambient light. This particularly applies to large units. For example, c side, d high side, e high, and many lighting people still miss the unique quality of the old f top light. The lens of the light is quite large, creating a good deal of wrapping while the small arc creates a light that is highly specular and sharp.
The wrapping gives it certain soft light characteristics while the small source keeps it clean and hard, very snappy. Although 12K HMIs have lenses just as large as those of the brutes, their slightly larger radiating source keeps them from having the kind of bite of a brute.
Also known as breakup, subtle gradations can be introduced into the light pattern by cookies, celos, branches, lace, charlie bars, sheers translucent window curtains , or other diffu- sion materials. There are the obvious ones: a car-headlight effect, a rising sun, and so on; but subtle movement of light can make a scene more realistic and alive. One frequently used trick is to place a branch or plant in front of a light that is coming through a window and then place a quiet fan so that it makes the branch or plant move very slightly.
This creates shape and shadows a on the camera side, adding depth and dimension. This is a broad generalization, of course; there are many exceptions to this, but as a general principle it is a good guideline to follow. This is both a speciic technique and also an illustration of a general principle in lighting. Often we want to make it look like the subject is being lit by a particular source that appears in the frame—in this case, a practical lamp practical means that it actually works.
Some Black Wrap is used to keep it from spilling onto the wall. Charlie bars vertical bars, in this case made from tape on an open frame and also some lace create texture in the scene. There are dozens of variables, but some of the most important are 1. Surface texture: diffuse versus specular.
Angularity versus roundness. Subject contrast. How dark or light the object is in terms of the gray scale. Also, the contrast between the subject and background or between different parts of the subject. These are the basic building blocks we work with on the set. Four typical methods of making light soft: a A very large source such as this giant Fisher Light makes a soft light, essential for jobs such as lighting cars. Photo courtesy of Fisher Light. A movie is made one scene at a time; a scene is made one shot at a time.
The same applies, of course, to commercials, industrials, music videos, and even documentaries. In this chapter we will select several scenes from features, com- mercials, and classroom projects. Whenever possible, a lighting scheme is planned well in advance.
In nearly all cases, there are deviations from the plan; this is normal. As a general rule, the lighting of a scene is built—one light at a time. With larger scenes, there is usually a prerigging plan. On the day before, the electricians, with perhaps a rigging crew, will lay out the cable and place the larger lights in preparation for the arrival of the shoot crew.
Even in these cases, however, there are always adjustments and these are generally done one light at a time. We only know a thing by its opposite. This adaptation will eventually lead the viewer to see the light as basically white.
Spreading moonlight over such a large area about two acres for all the scenes usually calls for a large crane or, at the very least, a couple of levels of scaffolding. Either might be a problem as they may appear in the frame at some point the trees are very low at this location and a crane might need to be moved: a time-consuming process in a rough location like this.
Scaffolding would be even more problematic. Fortunately, the location itself offered a solution. The site chosen with much urging from the DP was a dry wash at the bottom of a steep hill, which was about 60 feet high. At the top of the hill was the crew parking lot—the perfect spot to park the generator. These are simple iron pipes with holes drilled in them. This type of rig has several advantages. It is fairly constant, so it is good for continuity.
These are a Mighty Mole, a Baby-Baby, and a Mickie Mole on a triple header with all lights run through a three-channel lickerbox. See Figure 4. In the scene in Figure 4. First of all, it cannot be done with a single light.
One thing you will notice is that the shadows on the wall dance around. Having three diferent sizes of lights ensures that the efect will licker realistically— in this case a 2K Mighty, a 1K Baby Baby, and a 1K Mickie Mole. Three lights are always necessary for a convincing efect. Note the position of the grip arm that supports the triple header—it is set so that it can be lowered to the ground, which is often required for a campire efect.
The lickerbox has three channels, each of which can control a light up to watts. Each channel has independent settings for high point and low point and the licker rate is controllable in a wide range. For candle effects, special movie candles are available. These candles have three wicks and burn much brighter than ordinary candles. Group Scene with Fire Figure 4.
Establishing the source is an important part of selling the effect. This is not a danger in a scene like this, of course. The ire licker rig is camera right and slightly behind them. In front at ground level is another 2K moon effect softer, ire licker rig with three 1K zip softs. Fire flicker rig Low fire flicker rig Figure 4. One is placed on the ground in front and camera left of the group.
Figure 4. The white card bounce was used, as direct light that close would have been too directional, even with soft lights. The decision was to go all blue in order to give it mood and also disguise the fact that we had just an ordinary living room set. Double CTB was added to all the tungsten lights.
The Kino had daylight bulbs. A 5K with double CTB is outside the window, coming through venetian blinds. First of all, there were table lamps.
Film noir interiors always seem to have table lamps. The smoke and glow of the butane lighter add mood and texture to the shot. The other bounces off the typewriter paper as his key light. A Betweenie provides a small glow on the map in the background. Two Tweenies armed out on C-stand arms are the main units for the scene Figure 4.
One of them provides a back kicker for the actor and the second is the key light: its only task is to bounce off the white typing paper to provide a subtle underlight for his face Figure 4. An additional Betweenie gives a slight glow to the map and books on the shelf behind him see Figure 4.
The beam pro- jector provided a hot, sharp beam through the window. With full CTB added to the already blue HMI and the camera set on tungsten balance , it provided an intense mood for the scene see Figure 4. A desk lamp provided some color contrast and hot spot on his head—a focal point for the image Figure 4.
A Tweenie keeps the area under the desk from going totally black. Without the fog effect from a smoke machine, the shot would not have been nearly as effective. Detective Scene This scene Figure 4. Young Inventor The challenge in this scene is the lightbulb. From top to bottom on the left: with the bulb as the only source, it burns out. Instead, the bulb is dimmed down and is carried by a MolePAR through a snootbox.
Along with some light through the window and a backlight, the scene is complete see Figure 4. This means he looks like he is being lit by the practical, but it can be dimmed down to a good level. A baby with some full blue ills in a part of the table not covered by the MoleBeam.
A handheld LED panels serves as both a prop and a practical light b source. This Potter means he looks like he is being Figure 4. The lighting scheme was extremely dimmed down to a good level. In front of the actor working on the pottery wheel accent through the window, the was a window. Heavy diffusion in this case bleached muslin scene is complete. Beauty Shot Figure 4. Pool Room Figure 4.
Inside the light over the pool table, two watt bulbs were hidden. Coming through the window of the back room was a 5K. The scene was shot during the day, and the small amount of existing daylight that crept in gave the scene an overall cold, gritty feel.
At the climax of the scene, the actor moves close to the win- dows, and we see the real intent of lighting primarily through the wooden blinds of the windows. This is a good example of how the eventual key close-up of the scene shapes the thinking about how to light the wide shot. Although there are usually some adjustments to be made when you move to the coverage, the lighting continuity must remain somewhat constant.
It is important to be thinking several steps ahead as you light the master, so that it has some chance of working reasonably well for the coverage as well. Intimate Room Scene Lighting this scene was a bit trickier than might appear.
The blocking of the scene had them placed right next to the window. Outside was a terrace, but in most places where you might want to position a light, it would have been visible through the window. The solution was to partially close the blinds—placing them at an angle so the lights were hidden but the light could still reach the actors see Figure 4. It turned out to be a perfect angle to give each of them an upstage key that just reached into their downstage eye, leaving nice deep shadows on the downstage side of their faces see Figures 4.
With an arrangement like this, it is important to check the angle of the blinds and the lights every time the camera moves and then adjust them enough to maintain the same lighting look, but not so much as to interfere with continuity. Here we have a typical problem. As previously discussed, interesting lighting is most often achieved by bringing it from the back—getting the lights around to the sides and b behind the actors.
Frequently, this placement of lights would mean the lights are visible in the frame. In this case, they have even have been visible outside the window when we went for close-ups from either side.
Bringing them through the blinds gets them where we want while hiding them from the camera. Knowing how to hide lights in the frame is an important skill. Back Cross Keys Sitcom Lighting Here we see an attempt at bad lighting or, more simply sitcom lighting.
Situation comedy, indeed—all three-camera television—tends to be lit with the same basic scheme, called back cross keys. Each of the four soft lights held six watt bulbs ECA see Figure 4. The soft boxes establish an ambient base—an overall directionless light that serves as a base to build on.
This is supplemented by practical lights, a couple of PAR cans streaking down the wall, a zip light, and some 2K shooting in from the corner openings through half spun. In or Out? This classroom exercise aimed at a moody, low-key look. A bit of blue moonlight through the window and a practical lamp were all that was added to this scene. Dozens of Kino Flo tubes were removed from their housing and arranged underneath the elevated set to provide the primary lighting.
Photos courtesy of Kino Flo, Inc. In some cases, the ambient just forms a base on which to build with other lights. This was accomplished with several very large silks hung on trusses and large Kino Flo units suspended above them. Notice that the practical lamps china hats with watt BBA bulbs also play a role, but primarily as set dressing. Confessions of a Dangerous Mind: Alley A very simple scene but one that makes a powerfully graphic and memorable image.
This is an excellent example of the artistic subtlety, careful thinking, and preplanning that goes into a well-made lighting scheme, even on what may seem to be the simplest of shots. A smoke effect is also important to this shot. On a big studio picture, shooting is so expensive that anything that saves time in adjusting the lighting pays off in the end.
In the case of the ring of 10Ks, they are rigged on a circular truss that is suspended from the grid. A Ruby 7 with a skirt is hung directly above the actor. Grips handle this type of rigging, with assistance from the electricians when it comes to actually hanging the units.
Electricians then wire up the units in this case to the dim- mer system and focus them. The large units were the Storaro series of lights, most of which use volt ACL globes, which are aircraft landing lights and very punchy. Some were placed on lifts and some worked on the ground. Having so many units placed at such large distances makes it especially important to have them all on dimmers for centralized control.
In addition to lighting placement, this diagram also details power distribution and placement of dimmer packs, which are the actual dimmers controlled from a central dimmer board. The Storaro lights were invented by cinematographer Vitorio Storaro. A big set like this naturally requires a complex lighting design and extensive control. With lots of actors and crew standing by and the enclosed nature of the set, having electricians run around dropping scrims or having the grips set nets is out of the question.
The only feasible solution is to run all the lighting on dimmers. Naturally this involves considerable extra cabling—rather than just running power from the electrical source directly to the light, it is necessary to run power to the dimmer racks and then to the lights. There is extra expense involved as well, but for a large production the savings in time more than makes up for the cost and labor.
The second difference is separation in the shadows and highlights. HD video has an extraordinary response in the shadow areas, but all forms of video have trouble handling hot spots in the highlight areas. If there is one key concept to remember about HD and other kinds of video, it is this: Do not overexpose! Video simply cannot handle overexposure; once the signal clips, it cannot be saved. This not only pre- vents having the image changed for the worse in post, it also means that your scene will have a full range of tones, thereby contributing to a richer, fuller image.
The Video Engineer and DIT Between the video camera and the videotape recorder, one important link stands out—the video engineer. On HD shoots, this position has evolved into the Digital Imaging Technician DIT who not only has responsibilities for the integrity of the video signal but also manages the look of the image—generally, the DP will describe the particular look he or she is going for, and the DIT will make the adjustments to accomplish that.
In most cases, the DIT will also have the ability to remotely control exposure and other factors—not as a creative decision, but more to maintain consistency; this is similar to how a studio video shoot works—many camera functions are operated from the video control room. The key instrument in accomplishing this goal is the waveform monitor.
The waveform monitor is the light meter of video. The waveform monitor is basically an oscilloscope that displays the video signal. Using the waveform monitor as a technical and creative tool depends on an understand- ing of the video signal.
The video picture is formed by a scanning beam of electrons. This is not a new frame, however; it is the same frame again. The screen would appear to be dark in the upper left while the lower right was being painted. This is the more common usage. The actual minimum black level is 7. During the blanking inter- val the time when the scan line is moving back across the screen the signal goes to 0 units, which is important in keep- ing it invisible as it moves back to the other side of the screen.
The sync pulse, which is a trigger that signals the beam to begin to move back across, actually dips below 0, to —40 IRE units. These blanking and sync pulses occur outside the picture area, in the so-called overscan areas. This is also the representation of color as it is manipulated in the matrix menus of HD cameras. As this single trace moves across the screen, it records the relative brightness of the picture information.
It is exactly the same as a series of spot meter readings across the set from left to right in a straight line. Totally black areas in the picture will show up on the monitor as 7.
Bright areas will record as 90 or units or more. Where the picture exceeds IRE units, the video signal is overloaded. Video engineers will always try to keep the signal under units. The waveform monitor is an invaluable tool in lighting a scene. It can be used to set the overall brightness level, the contrast ratios, the iris setting, and to watch for any hot spots.
The pitfall is in being a slave to it. As a general rule, the lighting of the scene must accommodate the parameters of video. Remember that, even in video, what you see is not always what you get. The Vectorscope The waveform monitor tells us little about the color con- tent and balance of a scene—for that we need a vectorscope.
Hue is represented by degrees of rotation from the reference point and saturation is represented by distance from the center of the circle. These act as targets when calibrating to color bars. Iris Control Video cameras vary in sensitivity, but in general, they cur- rently run around to ASA this is an equivalent, as video cameras are not really rated in terms of ASA.
Because highlight areas are so much more problematic than shadow areas, the general practice in videography is to set the exposure for the highlights and deal with the shadows in another way. This would also lower the level of the face 20 units, which would make it appear darker than normal. We can set a net to keep light off the shirt, change the shirt to a darker one, soak the shirt in tea to tone it down, or add a little light to the face.
Electronic Pushing Another factor that affects overall exposure is electronic pushing or gain. It raises the sensitivity of the video sensor, allowing the camera to form an image at a lower exposure level. The boost is rated in decibels dB and each 6-dB boost is the equivalent of one stop. Most cinematographers prefer to shoot at —3 dB when the camera offers that option; this reduces noise to a minimum.
This is achieved electronically by white balancing. A relatively quick and simple process, white balancing is necessary only at the beginning of the day or when a major change occurs in the lighting, such as going from indoors to outdoors, or using a different setup with color gel on the lights. It may also be necessary if a camera starts acting up owing to overheating or other problems.
In either case it consists of focusing the camera on a white or neutral gray target such as a white showcard ; then you either push the auto white balance button or manually adjust the paint controls. Many advanced cameras have the capacity to memorize more than one white balance, which can then be selected later. When white balancing, it is key to know what your refer- ence is. You are shooting in a remote location that has very low voltage. The tungsten lights are burning very yellow as a result of the voltage drop.
You want to be sure you get good clean color. You have lit a set for late afternoon. In the case of the low voltage, you want to get rid of the yellow in the lights. In this case you would expose the white card with the yellow light from the set lighting units.
In the second case, the color is an effect that you want. If you exposed the white card to the light with the CTO or no-color straw gel, the white balance would remove the color and negate the effect you are trying to build. In this case it is necessary to have a neutral light available to white balance. It should be a light without any gel added, straight K or K, depending on the types of lights you are using. There is still separation from one area of tone to the next higher area, but the difference is not as extreme as it was in real life.
No matter how bright an object is in real life, it can only reach D-max. The bad reputation of video lighting is based on two historical factors: 1.
Video is frequently the lower cost alternative. A production company that is saving money by shooting video is unlikely to splurge on the lighting crew, equipment, and time. Video production is often multi-camera shooting. With some care and skill, however, it can be almost as good as single-camera lighting. There are two basic approaches. Find lighting solutions that work as well as possible for all camera positions.
This often involves broad sources and a more general lighting. Use dimmers to alter the lighting balance as the shot shifts from camera to camera. For a more generalized situation, an X approach is often used. For each position, there is a front left and front right unit and a back left and back right unit.
The dimmer operator is in control of the balances and which lights serve what purpose for each shot. It takes a good crew and a thor- ough rehearsal, but it can work well. Monitor Setup The most important thing you can learn about video is how to set up a color monitor properly. Even with other equip- ment such as a waveform monitor and vectorscope on hand, the monitor is still a critical part of previewing and judging the picture.
Color bars are recorded at the head of every videotape to provide a consistent reference in post-production. They are also used for matching the output of two cameras in a multi-camera shoot and to set up a video monitor.
On top on the left is a gray bar: it is 80 IRE units. It was generated at a central location in its facility and sent by wire to each studio. This way, all of the equipment could be calibrated conve- niently.
The middle black is set at 7. None of these really works to signal. The lightest bar on the right There should be no dividing line between these two bars.
The only division you should see is between To do so, turn the contrast all the way up. Now notice that the bands are of equal intensity and in the upper portion turn the contrast down until this white bar just begins the large and small bars are equally to respond. The image below shows what it should gray or black. It is possible to eyeball the yellow and magenta.
This is the down- and-dirty method and should be used only if other meth- ods are not practical. The yellow should be a lemon yellow, without orange or green. And the magenta should not be red or purple. This quickie method is not recommended except in emergencies. This applies to SD monitors only. In HD, it is not possible to adjust phase.
However, if you are using a downconverter on the camera with an SD monitor, this adjustment will still be necessary. A standardized test chart Figure 5. Blue-Only Adjustment Most professional monitors have a blue-only switch. This turns off the red and green guns, leaving only the blue Figure 5. If your monitor does not have a blue-only switch, you can use a piece of blue gel full CTB or a Kodak Wratten 47—the purest blue in the wratten series.
View the moni- tor through the gel. If you see any of the red, green, or yellow colors, double the blue gel over to increase the blue effect. By using the blue-only switch or a piece of blue gel, you have removed the red and green elements of the picture.
Only the blue remains. If the hue is correct, you should see alternating bars of equal intensity. You can also match either the gray or blue bars with their sub-bars. Each Tweenie has a double scrim in it to reduce the light. This is for setting backfocus, which requires that the lens be as wide open as possible. You can also match either of them with their sub-bars. Now the four bars—gray, blue, cyan, and magenta—should be of equal intensity. The yellow, green, and red which are black in Figure 5.
White balance is accomplished by aiming the camera at a pure white surface usually a white card and selecting the white balance function on the camera. The internal electronics then compensate for variations in color. The white balance function can also be used to fool the camera. A video camera records the image and then electronically processes the signal in a number of ways.
There are many things that can go wrong. Proper setup is essential and not merely for the camera. Each of these must be calibrated, of course, but it is also impor- tant that the entire system be coordinated.
To do this, two things are necessary: proper setup of the monitor to color bars and then calibration of the entire system using a proper test chart. A good test chart reveals many types of informa- tion about the camera, the monitor, the lighting, exposure, color balance, and much more.
Some of it is more for video engineers, but the basics are invaluable to the DP, lighting director, or camera operator.
A good test chart is absolutely essential to shooting on HD and SD svideo. Although the Chroma du Monde is optimized for daylight balance light, if tungsten is all you have, it will do. One feature that makes this chart so useful is the Cavi Black in the middle. It is a square hole in the middle with a black velvet box behind it: this creates an area of pure black for reference. Frame up the chart and set your optimum exposure.
With the pure black of the Cavi Black in the center, you can see where pure black lies on the waveform monitor it is also a good doublecheck on the video monitor. With the step grayscale, you can check the overall gamma contrast as well as the knee and toe areas to be sure they are within spec. Once you have adjusted the camera and monitor to a nor- mal rendition of the image, you can use these same refer- ences to establish any particular look you are going for.
The range of the grayscale, the pure black and the white areas, will allow you to see a more complete picture of what the image adjustments should be probably more than if you were just looking at a typical scene. The primary and sec- ondary color patches will allow you to see the effect of any color adjustments you make. Human eyes are sensitive to the small portion of that spectrum that includes the visible col- ors from the longest visible wavelengths of light red to the shortest wavelengths blue.
Intensity of light is measured in foot-candles or in lux in the metric system. A foot-candle fc equals about A foot-candle is the light from a standard candle at a distance of one foot. One lux is the illumination produced by one standard candle from a distance of 1 meter. It just gives us some standard points of reference. The Bucket Think of exposure as a bucket. This never varies, meaning that we have to provide it just the right amount of light. The quantity of light in a scene varies widely: the difference between a darkly lit interior and a sunny day is enormous.
This is the job of exposure control. A stop is a unit of light measurement. An increase in the amount of light by one stop means there is twice as much light. A decrease of one stop means there is half as much light. Thus, each stop is greater than the previous by the square root of 2. They all follow the same basic mathematical pattern. Modern digital meters measure in one-tenths of a stop. This is helpful for calcula- tions and comparisons, but for most practical purposes, this level of accuracy is not necessary.
One-third of a stop is the practical limit of precision, given the vagaries of optics, lab chemistry, and telecine transfer. This is not to say that accurate exposure is not important—only that the degree of precision in the overall process has limits. Changes in illumination due to distance with closed down. The inverse square law applies to point sources, strictly speaking, but spotlights follow it fairly well at the distances usually utilized.
This scale is tiered to make the relationships between intervals more easily seen. The scale may be expanded in either direction by adding or subtracting digits the intervals below 6 are 5, 4, 3, 2. Foot-candles: The ISO scale can also be applied to foot- candles. Doubling the foot-candles doubles the exposure. The third-stop intervals give the intermediate fc values. This can be helpful when unusual combinations of shutter angle and frame rate produce odd effective shutter speeds.
Table 6. Onto the base, the emulsion adheres where the photo- chemistry happens. There may be 20 or more separate layers coated here, each individually less than one-thousandth of an inch in thickness.
The imaging layers contain submicron-sized grains of silver halide crystals that act as the photon detectors. These crystals undergo a photochemical reaction when they are exposed to various forms of electromagnetic radiation— light.
In addition to visible light, the silver halide grains can be sensitized to infrared radiation. Silver halide grains are manufactured by combining silver nitrate and halide salts chloride, bromide, and iodide in complex ways that result in a range of crystal sizes, shapes, and compositions.
Spectral sensitizers are added to the surface of the grains to make them more sensitive to blue, green, and red light. These molecules must attach to the grain surface and trans- fer the energy from a red, green, or blue photon to the silver halide crystal as a photoelectron. Other chemicals are added internally to the grain during its growth process, or on the surface of the grain. These chemicals affect the light sensitiv- ity of the grain, also known as its speed—that is, how sensi- tive it is to light.
The prism splits the image into Red, ISO is the technically the correct designation, but by tradi- Green, and Blue components tion, most people still refer to it as ASA. These larger grains can result in a blotchy or grainy appearance to the picture.
These tabular grains are roughly triangular, which allows them to be packed closer together, thus reducing apparent grain. Other recent improvements include the family of Vision stocks from Kodak and technical innovations from Fuji. The useful property of silver halide is that its state is altered when subjected to light, in direct proportion to the amount of light energy absorbed. The activity of the developer and time of development will determine how much of the sensitized halide will be converted.
The Latent Image When the shutter is open, light affects the chemistry of the emulsion and a latent image is formed. When a photon of light is absorbed by the spectral sensitizer sitting on the surface of a silver halide grain, the energy of an electron is raised into the conduction band from the valence band, where it can be transferred to the conduction band of the silver halide grain electronic structure.
This atom of silver is unstable. However, if enough photo- electrons are present at the same time in the crystal lattice, they may combine with enough positive holes to form a stable latent image site. A latent image site must contain a minimum of 2 to 4 silver atoms per grain to remain stable. A silver halide grain contains billions of silver halide mol- ecules, and it takes only 2 to 4 atoms of uncombined silver to form the latent image site.
Below the inertia point, no image is recorded at all. Video receptors are silicon-based and, of course, are different in operation, but the basic theory is quite similar. As a result, the development process is easier to understand.
Those grains that have latent image sites will develop more rapidly. The unexposed grains remain as silver halide crystals. The material must be removed or the negative will darken and deteriorate over time. Then it is dried. The washing must be extremely thorough. It is a negative in the sense that it is darkest has the highest density of opaque silver atoms in the area that received the most light exposure.
In places that received no light, the negative is clear. These translate roughly into red, blue, and green. Oxidized developer is introduced into this reaction, and the oxidized developer reacts with chemicals, called couplers, in each of the image-forming layers. This reaction causes the couplers to form a color, and this color varies depending on how the silver halide grains were spectrally sensitized. A different color-forming coupler is used in the red-, green-, and blue-sensitive layers.
Note: it is possible to skip this step or reduce it so that some of the silver remains in the negative. Cyan is a mix of blue and green or white minus red. Universal Principles of Art is a comprehensive reference for all artists, and a follow up to ….
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