A combination of an incident meter and a spot meter is used for a triple light-measuring technique for some difficult exteriors. Adam Holender suggests the following:
1. Measure with incident meter pointed toward the camera.
2. Measure with incident meter pointed first toward the sky, then toward the ground, and split the difference.
3. Measure with a spot meter to evaluate the subject selectively.
4. Decide the exposure in relation to what is important in the frame.
As we see, on an exterior location where a cinematographer has less control over the lighting, his measuring methods have to be much more exact than in the studio. Backlit scenes silhouetted against the sky require especially careful interpretation. A spot meter can read the highlights and the shadows. There will be a few stops’ difference between the two. If we are not using any fill light, we have to interpolate the best exposure for the mood we wish to create: how much to overexpose the sky and how much to underexpose the face, and where the background will be in the exposure—for example, hills silhouetted against the sky.
Besides using an incident-light meter and a reflected-light meter, some cinematographers like to test their contrast ratios by taking a digital still photo.
Finally, a few words should be said about the viewing glass or contrast filter. It is basically a filter of a certain density designed to evaluate the contrast as it will be rendered on film. For black-and-white film a Kodak Wratten filter #90 (olive) is used and for color film it is a neutral density of 0.9. Unfortunately, at a low key, a viewing glass is not very useful.
John Alonzo, ASC
I use a contrast viewing glass just as a reference point. Not always, but sometimes when I have a slight problem like shooting a man against a window, it helps me to evaluate.
All the light meters and other devices are just tools to help in shaping the aesthetic concept. The art of filmmaking should never become subservient to technology. An understanding of the scientific processes employed, though, will make the cinematographer less dependent on the measurements. The old adage that you have to know the rules to break the rules is truly illustrated in exponometry and in cinematography as a whole, so the rigid ratios between the key and the fill light should have their place mainly when shooting tests. In the end, it is often intuition that wins out over all the measurements and contrast-viewing glasses.
Caleb Deschanel, ASC
As far as the direction of light and the amount of fill light, that part of it is really by eye and is more intuitive. You make a decision about how you want to see something, and it can be partially a conscious decision and partially how you feel about it. Sometimes you just feel that you should do something a certain way. You have to answer to that. Good directors will respond to those intuitions and will accept them as an equally practical means for making a judgment as being intellectual about it.
Oftentimes you give yourself a reason for something after the fact. People demand a reason for your doing something a certain way. But it makes no sense to spend a lot of time coming up with reasons when you are dealing with an inspiration or intuition. You should be able to say, “Well, I don’t think that’s right.” I mean, that is my feeling.
Just as cinematographers must be aware of whether their eyes are tired when they’re judging the brightness range, it is also important to remember that the human eye adapts quickly to slight color shifts in light unless there is a reference point in the field of view—for example, one area of true white light.
Picture and Waveform Monitors
Video production should provide the cinematographer with a set of instruments to evaluate the captured image. Here a good monitor in a darkened space is essential. Further yet, the distribution of the brightness range should be displayed on the waveform monitor.
M. David Mullen, ASC
I only used the waveform monitor on my last Genesis show, because they had the budget for one. I have been shooting without one for most of these years. Traditionally, when I was operating on HD shows, I just used the zebra in the viewfinder, which I would set to appear at 70 IRE [on the waveform monitor IRE scale], which is about the light gray or the Caucasian skin tone, or you can have it appear at 100 IRE, which is white. So that is an exposure guide. Usually if you have a well set-up monitor in a good viewing environment, you can see noise problems and you can see clipping problems. You can set your exposure pretty well with a good monitor. This is how most of my things had been shot. With a waveform monitor on my last show, I used it when I was filming in extremely bright locations. I could double-check how much I was pushing my information at the top scale.
I still use an incident meter to set the key and then I judge everything else by eye and by the monitor. You could use a spot meter, but you would have to come up somehow with a system to calibrate what the spot meter readings are giving you versus what the range of the camera can handle. But since I never developed the habit of using a spot meter in film work, I don’t use it in digital work either. Exposing the subject is easy in the digital; it is the extreme ends that you have to worry about, and sometimes it is just a question of setting the exposure where you think it should be by looking at it. And if you have a certain amount of clipping in bright areas, you can do something to control that, either by adjusting your lighting or by slightly underexposing the image to get more details onto the recording, so you have it there when you’re doing your color correction later. It is always a tough challenge between noise and clipping, because with any digital camera if you underexpose to get more exposure information in highlights, you get more noise if you try to correct it later, and if you overexpose it to reduce noise, then you have clipping in the overexposed areas.
So far the Genesis camera is like a 400–500 ASA tungsten, the F900 is more like 320–400 ASA tungsten. The Red camera is a 250–320 ASA daylight, ideally. In image processing, lookup tables (LUTs) are used to create a new output value for a certain input value. The most common application of LUTs during production is when the camera is using a log gamma emulation but the cinematographer wants to view the image with the correct Rec 709 gamma for a monitor display. Without the LUT transformation, the log image would appear low in contrast, with weak blacks, dim whites, and pastel colors. However, LUTs can also be used to create different “nondestructive” looks that can be applied to both the on-set monitor image and toward any dailies made from the original camera tapes without actually affecting the log recording. The Panavision Genesis runs the monitor-out signal through an external LUT box called the GDP (genesis display processor). You can either create the LUTs on set using a laptop, or you can load LUTs into the GDP that were created at the post house. The same LUT used by the GDP can then later be applied by the post house when making dailies from the camera tapes.
Steven Scott, colorist
A lookup table is, in essence, an emulator. In other words, we have a lookup table that is capable of emulating what a print on standard Vision stock from Kodak will look like, or what one will look like on Fuji stock. We emulate the look of a particular stock or digital medium that we go out to.
Color Gelatins
The two essential color gel series to adjust or change the color temperature of light are the CTO (color temperature orange) and the CTB (color temperature blue). They come in a range of densities from one-eighth to full and double CTO and CTB. There is also a wide array of color gels available from gel manufacturers like Lee and Rosco. Swatch books of their gels are very useful to have around.
Generally we can say that cinematographers today are much more daring in their departure from the exact color temperature of the light required for a given film than were their colleagues a few decades ago.
Allen Daviau, ASC
I rarely like the normal 3200K for anything. I like to use the pale gold 54 gel in different strengths as a warming element, unless I am representing something right near a white light where it would be normal. For the feeling of a lamp shade or what have
you, I would throw a 54 gel on all my source lights. It does not read golden, but sometimes you will see the backlight bluer than if the same light was coming from the front. And if I throw in a 54 gel, it will make it neutral. Light loss on the 54 is negligible, very slight, unless you double or triple it.
Jordan Cronenweth, ASC
Color is relative. If you want to have a warm feeling to a scene, you need a nonwarm reference, otherwise the eyes will adjust and pretty soon they are seeing overall warm as a more neutral color light. But if you keep a reference in the frame, like another practical that is not as warm as the one you are using or a reflection of something in a mirror, that gives you a reference. As long as you keep that alive in there, the audience will never start assimilating the warm light as normal light. In a day interior scene with the feeling of the daylight in the windows, put the practicals on in the room. People will have nice warm light from the practicals, and yet when they come by the window, they will be in daylight (accentuated by a colder light). As far as unfiltered windows on locations are concerned, I personally don’t like that much difference in the color temperature. I am particularly sensitive to blue; I don’t like it.
Another way to warm up the lights is by putting them on dimmers to lower the color temperature (in degrees Kelvin). For this purpose as well as for the adjustment of brightness, practical lamps are often used with a rheostat on the line.
On location, and even on studio sets, fluorescent tubes are sometimes left unfiltered for a more realistic feeling. But when filtering is needed and tubes with correct color temperature are not available, conversion gels and color-compensating and color-correcting filters can be used.
The aim in filtering is to obtain a uniform color temperature of all the lights so that the laboratory can correct it during the timing of the print. If natural daylight prevails and the tubes are also fluorescent daylight or cool white, the windows can be covered with a green gel called full plus green. If we wish to use tungsten 3200K lights simultaneously, we need to cover them with plus green 50. Should day-type lamps like fay lights be used as well, the proper gel would be full plus green.
When the lighting situation indicates that it is more convenient to filter the fluorescent daylight tubes rather than the windows and tungsten lamps, full minus green gels are employed, sometimes in the form of sleeves for the individual fluorescent tubes. The minus green-covered tubes create a disquietingly purple illumination and often a color temperature meter is needed to put us at ease that this “purple” illumination will indeed match the daylight.
A scene entirely lit by fluorescent light can also be corrected with filters used on the camera lens. Several companies offer two filters, FLB and FLD, for the correction of the average fluorescent tubes of the warm and daylight types respectively.
Finally, a few words should be said about correcting fluorescent illumination that does not match the film emulsion during the timing in the lab. Let’s remember that timing deals with the whole frame and can be totally effective only when all the light sources we wish to correct are the same color characteristic. There is also some danger in full fluorescent correction.
Allen Daviau, ASC
It is no problem for the lab to make the fluorescent correction. The one thing I will caution you about is allowing the lab to make the full fluorescent correction. There is something that occurs in removing all the green from the print that raises the inherent contrast. And then you’ll get an extremely hard black, harder than I like. As a result, when I am shooting in fluorescent, I tend to use a low-contrast filter, like Tiffen LC 3. And people will say, “Isn’t that strange, you are shooting under fluorescent light, it is so flat, why would you want to use a low-contrast filter?” But I found out the hard way that without this correction you’ll wind up with extremely contrasty blacks.
Image Manipulation by Filters, Nets, and Other Optical Media
The cinematographer has an impressive range of filters and nets at his or her disposal, to manipulate an image in the camera. Some, such as graduated filters, are employed to selectively change the density of the image or, like low-contrast and fog filters, to change the contrast of the image. Others, such as diffusers, are specifically used to soften the definition of the image.
The first thing to remember is that any filter, particularly a glass one, will have an effect on the performance of the lens.
Ralph Woolsey, ASC
When the camera has inside filter capability, I would use it every time possible, chiefly for convenience, plus the advantage of not having to look through a heavy filter when operating. It is easier to make quick changes or to divide filter combinations. The main problem in having an inside filter is that it must be far enough from the film so that an imperfection or accidental piece of dirt will not produce a sharp shadow. And since the image is shifted about one-third the thickness of the filter, the usual rule of thumb is not to use inside filters when shooting interiors. Certainly avoid them if you are working wider than T/2 unless you can critically eye-focus. And of course the focus is much more critical with a wide-angle than a long-focus lens.
The most commonly used filters in the group discussed here are neutral densities. They allow the cinematographer to use wider lens apertures (f/stops) by cutting down the amount of light, mostly on bright exterior locations.
Caleb Deschanel, ASC
If I stop down to f/22, it is usually on a really long lens. With long lenses I always like to shoot as far down as I can for depth of field. For anything wider than 200mm I would use neutral densities. Generally, the NDs I use are Pancro Mirrors. They are a little more accurate. They are special filters that are mirrors basically, a certain percentage mirrors. When you go to N. 9 in ordinary filters, you will get a certain amount of yellow, which you will not get with Pancro.
A neutral density filter that does not cover the whole frame comes as a graduated or an attenuator. The graduated filter (also called grad or graduate) has a soft bleed line that separates the ND part of the filter from the clear part. Custom-designed filters may have this dividing line at different levels and angles to fit a particular horizon line or other frame division.
Vilmos Zsigmond, ASC
Sometimes I use an attenuator to make the sky look more dramatic, but it is difficult to use it when the camera moves a lot and I do not like to limit my director. I don’t want to tell my director, “You cannot move the camera now.” I do not like static filming, which works best for graduates and attenuators. I like the camera to be free to move all the time. It’s very difficult to have it both ways, to have camera movement and still use graduates or attenuators.
As we will see in the section on digital intermediate, the attenuator can be emulated digitally, in which case this effect can move freely with the camera movements.
For creating a darker and more saturated sky, blue graduates are also available. For a sunset effect an orange graduate can be used. Filter manufacturers can make grads to order in various colors. At times the blue sky can be darkened by using a polarizing filter a.k.a. polarizer or pola, if the sun is to one side. It polarizes the sky more than the foreground scene, so there is no problem with the bleed line of a graduate. But panning is also problematic because the change of angle in relation to the sun will also change the rate of polarization. At high altitudes the sky is usually sufficiently dark by itself.
Ralph Woolsey, ASC
Because the sky at high altitudes appears darker, the use of a pola filter can make it really black if desired. This filter is very useful, not only as an ND but also for its added angular capabilities. The angle can be changed during a shot in order to obtain certain effects. Reflections in a glass surface can be eliminated with a polarizer, and then on cue the pola can be rotated to fade in a reflection or ghost effect.
Modern lenses render the image with high definition that is often too harsh for the given subject matter. Several filters have been designed to diffuse the image, lower the contrast, and desaturate the color in va
rious degrees. In this group are diffusion filters, single and double fog filters, low-contrast screens, frost filters, Harrison’s Black Dot texture screens, nets, and several filters for specific effects, such as star filters. Most of these filters come in a range of five densities. Finally we can use clear optical glass smeared with substances such as petroleum jelly or glycerin.
The use of all the filters discussed here requires tests to arrive at the desired effect under the conditions of the given film stock, lighting, photographed subject, and expected processing in the laboratory or digital intermediate. It is important to keep in mind that this discussion on diffusing filters pertains mainly to 35mm and larger formats. The 16mm image is generally softer and on the whole does not need more diffusion unless special visual design demands it.
Any filter positioned in front of the lens may cause car headlights and other bright sources to appear on film as double images. To prevent this phenomenon, some cameras (for instance, Panavision) can be equipped with matte boxes that provide filter holders positioned at an adjustable angle so that the filter plane is not parallel to the lens surface. This allows the troublesome reflections to be directed away from the lens.
Cinematographers often differ in their preferences for certain filters. Here are several opinions.
Vilmos Zsigmond, ASC
Double fog gives a little glow from the highlights, which seems to me to be similar to the way the eye sees. I do not think that people see in clinical, sharp detail; I think that the human eye is more kind, softer. You do not see the pores in the people’s faces as a sharp Cooke lens does. You usually do not come that close to the person. So I think that the diffusion on the lens makes it more realistic.
Film Lighting Page 13