In Europe the voltage is usually 220 to 240. In this case 2000 watts divided by 240 volts would equal a little over 8 amps. With the greater voltage, the same lamps will require less amperage. For this reason European houses generally have lower total amperage and a 13-amp fuse per circuit is common.
Fuses and breakers are designed to safeguard against overloading the wiring designed for certain amperage. Therefore, replacing a fuse with a larger one is extremely dangerous. It will cause the wiring to heat up and may cause an electrical fire. For professional filming, the generator is the most commonly used source of power. The direct current produced is much safer for the crew. As Richard Hart puts it, “What happens with DC is that it hits you and throws you away. It literally kicks you back. The AC holds you.”
Today, because of HMI lights, many generators can produce both DC and AC currents with a 60-cycle governor. Generators come in a variety of sizes from a 2000-amp giant to a typical 1000-amp, a 250-amp, and down to a portable generator called a “putt-putt” that can provide 90 amps.
On a location where a generator is not available, one has to depend on the power coming to the house from the power company supply system. If the household circuits do not provide enough amperage, it is often necessary to draw it from the power main. Tapping into such a source is known as making a tie-in or a clip-on. This operation should be done by a certified electrician, as it is hazardous both to the person and to the system. On the film crew, a professional gaffer and his best boy should be qualified to do this job. If they are not, another electrician should handle this procedure. Some states have more restrictive laws than others. It would be wise to familiarize yourself with local laws.
The tie-in is done at the service panel of the building. Before tying in, connect the other ends of the cables to a secondary location panel (fused distribution box), so that there are no loose cables with “hot” ends. The placement of a secondary fused panel, or switchboard, between the service panel and the lights is required by the safety commissions in many states. When all the connections are completed, the switchboard may be used as a general switch for the lights in one area. This way the main service panel is protected from excessive surges of electricity because the fuses in the switchboard will be the first ones to blow.
Richard Hart, gaffer
A lot of times on natural interiors, small rooms, and so forth, what we like to do is to put in a remote switchboard so that we can cut the power to save the heat. In between shots you just flick the switch and all lights go off. When you are in the studio, a lot of times the wall is unfused, so you must use one of those remote boards or a switchboard of some sort that is fused.
For the proper connecting and distributing of the power, we should be familiar with cable sizes. They are rated in AWG (American wire gauge) numbers, which are usually marked on the insulation. The heaviest cable is rated 0000, and a typical gauge to handle a 5K light at up to 100-feet extension, or a 2K light up to 200 feet, is an 8. A 10K will require cable sizes 4 and 2 for 100 and 200 feet, respectively. On the other end of the power demand, a 500-watt bulb can be used with a 100-foot cable gauge 16.
Cable with an inadequate capacity will warm up from overloading and eventually melt or crack the insulation, the plug, or the switch.
There are a variety of cable connectors and they should always be checked for compatibility with each other and with all the distribution equipment, such as plugging boxes, splicing blocks, and spiders.
Working with lights, especially on location, requires constant alertness and common sense. The cables should be secured with gaffer tape and/or ropes so that people do not trip on them and pull down the lights. Especially cables tied into the service panel should be protected from an inadvertent disconnection at this point. A C-clamp attached to some structural element above the service panel can act as a support for ropes securing the cables. The location light stands should have no wheels so they are less subject to unintentional movement.
On wet locations, the use of AC should be ruled out as much as possible, unless all the necessary grounding of lights is rigorously observed. To protect cable connections from dampness, seal them with a silicon gel. For your personal safety, avoid holding a lighting fixture in each hand. Faulty wiring inside the light may cause the current to travel across your body. It would be particularly dangerous if these lights were drawing power from two separate current phases. The potential between them would amount to 240 volts instead of 120. It is therefore an essential safety rule that in a situation where the original 3-phase, 240-volt electrical supply is divided into two 120-volt legs, the cable distribution is arranged in such a way that lights on one phase are at a safe distance from the lamps powered by the other phase. Be alert and be careful!
Chapter Three
Image Manipulation
There are many variables that affect the quality of the image that is finally projected in the theater. The more control the cinematographer has over these variables, the better the chance of capturing the precise visual effect the cinematographer and the director desire for the movie. There are three stages of the filmmaking process where the cinematographer can manipulate the image. The choice of film stock or digital camera is the first stage. The characteristics of the film stock or video receptor the cinematographer chooses will affect the color or tonal rendition of the image and the exposure levels used. The second stage is the shoot itself. The cinematographer’s decisions about the range of brightness within the frame, which will be created through lighting, will profoundly affect the look of the picture. Filters or nets on the camera and manipulation of the environment through the use, for example, of fog or rain machines are other ways the cinematographer can control the appearance of the captured image. The last stage for manipulating the image is in the lab or, today, most likely in the digital intermediate (DI) suite. The film can be processed normally, be push-processed or pull-processed, or be otherwise manipulated to achieve a desired result. Once the film has been developed, the timing of the print is the final—and some feel most important—stage in the lab. On the other hand, if the negative is transferred to a digital medium, then the digital intermediate offers vast possibilities of image manipulations. Actually, when an image originated on a film stock goes the digital route, most effects offered by the film lab can be achieved at the digital intermediate stage.
Film Stock
Although the majority of important commercial films made in the Western world at this writing are shot on Eastman Kodak color negative, a large number of filmmakers are also using Fuji color negative to obtain a more pastel color quality. There have been cases where both stocks were used on a film; for example, to indicate a separation between two time periods. There are also good reasons for mixing films of the same brand but at different speeds. Fast films are recommended for night exteriors to take best advantage of the available light. Using the same film on a day exterior would require neutral density filters to work at an acceptable f/stop.
Digital Cameras
The world of digital cameras is changing so fast that it is impossible to predict the state of the art even six months ahead. M. David Mullen characterizes some of the digital cameras he uses.
M. David Mullen, ASC
I shot a lot of features digitally in the years after the Sony HDW-F900 HDCAM camera came out in 2000; before that, I was shooting in 35mm mostly. My first digital feature, Jackpot, became the first 24p HD feature to be released theatrically in North America. Because of that, I did several more films on F900. But over recent years, as the budgets of the features I was hired to shoot went higher, I went back to shooting on 35mm film. In 2008, after I did a 35mm feature in Canada, brothers Michael and Mark Polish (who made Jackpot) called me to do two independent features back to back. They wanted to shoot them digitally, partly to save costs. We ended up picking the Red One camera. As soon as I finished those two movies, I started shooting a TV series for Showtime called The United States of Tara. We used the Panavision Genes
is camera for all three seasons of that show, and since then I’ve also shot on the Red Epic, the Sony F35, and the ARRI Alexa.
Digital cameras have certain color temperature biases that they prefer. Generally they have less noise when shot in daylight balance due to the fact that sensors are less sensitive to blue wavelengths. The original Red One camera looked best, noise-wise, when shot at the 250–320 EI range and in daylight balance, although the Mysterium-X sensor upgrade allowed shooting at much higher sensitivity ratings due to the lower noise floor. The Pana-vision Genesis and Sony F35 cameras are more in the 500 EI range, and people routinely shoot the ARRI Alexa and the Red Epic at 800 EI and higher. With improvements in noise level, overall dynamic range is improved because more shadow information becomes usable.
Video cameras traditionally generate broadcast-ready images within a restricted contrast range and color space called Rec. 709. But modern high-end digital cameras record images with color and dynamic-range information that exceeds broadcast video limitations. This brings digital photography closer to what we get with color negative film.
Since negative film naturally has a logarithmic response to light, when digitized it is often stored in the 10-bit Cineon log format. HD cameras like the Panavision Genesis and Sony F35 use a log gamma emulation that allows the recording to go through the same digital intermediate workflows used for film. The digital image behaves more like a film scan in the color-correction process, plus there is more information to work with compared to something shot in broadcast video gamma.
Although shooting in 4:4:4 mode is preferred, most of these cameras look acceptable using 4:2:2 color subsampling, especially for television work. The term 4:4:4 just means that there is an equal amount of information per color channel in terms of the bandwidth; 4:2:2 means that the red and blue channels are allotted half the bandwidth compared to the luminance channel, which carries the green information. But practically speaking, it doesn’t necessarily mean that you have half the visible quality in reds and blues, or that you have “better” greens. With negative film, even though it is technically “full color” since it uses no chroma subsampling, there is less sharpness in the red layer than in the blue and the green, and the blue layer is the grainiest. So you can’t really say that color film has equal resolution in all color layers. Shooting 4:4:4 versus 4:2:2 tends to be more important when you do things like composite work using a chroma key, when you want maximum color information in order to make separations and create mattes. In practical terms, you can expect a little more color “richness,” or depth, when working with 4:4:4 footage in color correction compared to 4:2:2.
Terms like 4:4:4 come from the video world; film scans store color information as RGB data. Roughly speaking, television production involves a “video” workflow often using subsampled color and compressed video signals, whereas theatrical feature work follows a “data” workflow using full RGB color and uncompressed data. However, there is no real distinction between “video” and “data”—in truth it’s all data, i.e., digitized information. And some television shows are finished using feature-style digital intermediate technology, while some features are finished using traditional video workflows.
A few cameras record “raw” data. A single-sensor camera uses a color filter array (CFA) in front of the sensor, containing a pattern of red, green, and blue filters. In comparison, a traditional video camera uses three sensors, one for each color, with a prism block in front of them to split the light three ways. Most single-sensor cameras use a Bayer mosaic pattern, but a few use an RGB-stripe pattern. These color patterns have to be processed in order to see a full color image—for example, you often hear the term “demosaic” to describe the processing of a Bayer pattern into color. Therefore, recording a raw signal just means recording the sensor data without processing it first into color. In post-production, there will be a “transcoding” step to convert the raw footage into various formats, depending on your needs.
All single-sensor cameras have an internal processor to convert the sensor data to color, otherwise you couldn’t see an image in a viewfinder, but for some cameras, this conversion is not done at the highest possible quality (to save on processing work) because it’s only meant for viewing live on a monitor or viewfinder, not for recording. Other cameras will process the data into color for recording and instead do not offer a raw option. And others allow both types of signals to be recorded.
We are currently in a period of transition; the postproduction world for the past decade worked with either broadcast video footage or with film scans. By the middle of the decade, high-end digital cinema cameras emerged to record images with more dynamic range and color information, which could be handled by the same 10-bit log RGB digital workflow designed for scanned negative film. However, as film declines in use for origination and projection, it is likely that postproduction will begin to work with raw camera data at higher bitrates in its natural linear form.
Dante Spinotti, ASC
Digital is changing the way we make films and in some way it is changing the language of cinema itself. I shot recently on the Sony F23, which is like 16mm film, but Genesis has a 35mm chip, so there is a different optical look between these cameras, a substantial difference in terms of the depth of field.
As far as the dynamic range, you can adjust these cameras and make them work for whatever image you are looking for. It is possibly true that the digital range on some of these cameras is a little bit narrower, definitely narrower than film. The film negative has a huge extension of T/stops, which you can use from light to dark. I recently shot for two weeks on film. The first day we were shooting and we printed dailies on film. All of a sudden I said, “Look at these shadows; I don’t see any details.” So it is true that the negative has a huge extension in the latitude, but not the positive. I would say that the positive goes in the same range as the digital camera. In digital, I personally never have a problem with highlights. There is no doubt that the new Sony F23 has definitely an extended range in the highlights. If you had to use only what you are shooting in digital form, you probably wouldn’t need any waveform monitor. But because you are finally transferring it to film, you need to take a look at the instruments, only because in preproduction you usually do some tests. You know that if the face is 21 percent on the waveform scale, or whatever, it is on the edge of having the correct exposure. Below that it might give you some noise, unless you have a bright background, for instance. So, in preproduction you do some tests through the whole chain, the whole pipeline. You have to go from whatever you shot, through transfer, to negative, and then to positive. That gives you some parameters of what you can and what you cannot do. That is why you have to use the instruments.
I don’t think that you have to use light meters. I never use light meters anymore. I just leave them at home. I think digital takes you into an entirely different visual approach, especially if we are talking about night interiors and exteriors. I think that what is exciting about digital shooting is that you are not subject to the slavery of the meter. In other words, when you use film, you walk into a location and you know that you have to do some lighting. The director will rehearse with actors, and you know that in this particular part of the image you will have to expose, for example, at T/2.8, because the zoom is f/2.8, so you have this kind of slavery. With digital, you don’t have this slavery. You can walk into a space and decide to do whatever you want even in very low light levels. The camera has a huge potential for adding exposure, adding a stop, going to 360 degrees on a shutter. It gives you an approach free from technical constraints.
Also we know that the curve of a digital camera doesn’t have a toe; it goes up directly. So from the moment you see anything in the shadows, you are sure you are recording a huge amount of detail. So the realistic approach is very different. You have to trust the digital imaging technician entirely. He is a very important person on the set. He will tell you what you can do in terms of contrast and exposure. He will tell yo
u in critical conditions what your exposure is on a particular face. He also has a role in the creative input, in creating the look.
Digital has some tricky aspects. If you expose too much, you will have some digital aspects to the lighting in the shot, some shiny artificial look. To get out of it, you have to simplify your lighting pattern.
So what I really like about digital is this potential to walk into a location and use it without the Hollywood lighting. It is not that you have to adjust your lighting to digital rather than film. To me it is that digital is allowing you to go in a different direction, so you can choose to do things in a different way. There are smaller technical needs. If you do a cross light on somebody’s face or a backlight, or a three-quarters light, you need to be careful about overexposure because part of this key signal will be clipping in, out of the exposure range, and the result is not pleasant on a human face.
It is all relative, because the more tools you have, the more difficult the stuff you are trying to achieve. I find the major thing about this digital revolution is that you see right away what you are doing for the first time in the history of filmmaking. And that gives you a whole lot of confidence in doing different things and much more power to go in various directions.
Brightness Range Manipulation
The character of a picture will be profoundly affected by the range of tone values from light to dark and by their distribution within the frame. Light falling on reflective surfaces or shining through translucent materials produces various brightnesses. In black-and-white cinematography, they are reproduced as gray values. In color cinematography, the brightness is greatly influenced by the hue and saturation of the colors, but the final outcome is still a range of light values.
Film Lighting Page 11