Accademia della luce - educazione alle tecniche della luce

Cinematography
Date: Venerdì, agosto 30 @ 10:08:31 CEST
Topic: Educational Lighting Site
On the film scene the lighting design aims at creating special effects, which determine a“vision surplus” for the eyes of the spectators.
Lights, contraptions and devices all contribute to create a simulation and imply an increasedperception of the space of the scene. If cinema is image, then light matter is obviously itsprimary factor.
In fact, a film is written with light and thus becomes style, narration, atmosphere andstresses, emphasizes, alludes, it creates transparecies, it bestows dream-like and talecomponents on reality, it shows the relationship between things and people. A properlydirected reflector can uncover, on a poor scene, enchanted prospects, and its beams of lightbecome like small brushes that create the film, which is indeed a mixture of lights andshadows.
Light and shadow are thus the basis of cinema, the possibility of its existence.
Approximately two thirds of a film are shot in a studio.
In addition to natural light, artificial light is also used for external shots, either to enhanceor to reduce the contrast between light and shade, and to focus one’s attention on animportant detail. The basic principles described in the photography section also apply to film-making. Themethod is similar to the one used for television, with the difference that film shootingconsiders only one cinecamera. This ensures a considerable advantage as regards accuracyand lights, compared to TV shooting with more telecameras.
In film-making, the basic light and the supplementary key light are not necessary as, asalready mentioned, only one cinecamera is required and the use of lights remains the sameas in a TV studio.
The sensitivity of the film determines what Watt power to employ. For instance, a 25 ASAcolour print film will require twice as much light as is needed by a telecamera.
In this case it will suffice to increase the dimension of the beacons: a 2 to 5 Kw projectorwith Fresnel lens; a 2 a to 4 Kw soft-light, etc. The ratio between the sensitivity of the ASAfilm, the values of the lens aperture (f-stop) and the exposition time establishes the quantityof light (lux) necessary for film shooting.
The following table shows such ratio:f-stop f/2 f/2,8 f/4 f/5,6 f/8lux 400 800 1600 3200 6400In film-making the key-light is produced almost exclusively by projectors with Fresnel lens.
Daylight projectors are similar as regards dimension and lens, but they differ in relation totype of lamp; in normal projectors 2 to 12 Kw halogen lamps, with a colour temperature of3200K, are installed.
In Daylight projectors the lamps are 575 to 12000 watt discharge lamps, which can emit alight with 6500K and plus colour temperature. The filling light is usually produced bysoftlight diffusers or by devices called “bruto”.
Since only one shooting at a time is taken into consideration, the beacons are generallyinstalled on mobile tripods in order to be able to easily position them for each shooting.
When shootings are realized in a studio, the beacons are positioned by means of Americantrusses, galleries, parts of the scenography that are not framed, dollies etc.
The control of light intensity rarely requires a regulation system (dimmer + mixer).
The beacons are normally positioned and pointed towards a specific direction by means ofgauzes, tulle, and diffusers with different light transmission characteristics.
Light sources that are typically used for film-making, and also for television, can originatefrom a back or lateral position with a low angle (shoulder height); their task is to reinforcethe outline of the face.
In order to add sparkling to the eyes it is necessary to position an eye-light or basher asnear as possible to the cinecamera.
Beside these “special” projectors, there are other devices that alter the characteristics of lightwhen they are placed in front of a beacon.
Light shades, french flags, drums, are structures made of opaque material (blackenedsheets) that when placed in front of a light source control its ray, generally “masking” areasof unwanted light. Gobos are heat-resistant models made of alloy, which reproduce variedpatterns on backdrops, scenographies, people, and which are used together with projectorsequipped with an optical system with which it is possible to focus (beamshapers,followspots): the nosecone is a usually black funnel made of metal or heat-resistant fibre,which is placed in front of a Fresnel beacon on the ”flood” position in order to reduce theray of light without increasing its intensity; in other beacons the nosecone has the functionof eliminating false light.
For external shootings, but sometimes even inside a studio, variously dimensioned screenswith different kinds of reflecting surface are used: slightly mirrored, granular or mattedsurfaces.
The function of such screens is to fill shadowed areas with light. The filters are mostlyconversion or neutral density filters. o It is advisable to avoid white backdrops or spacesthat are set to close to the face of the subject to be filmed.
o A dark dress against a dark backdrop reveals neither any colour nor any form. o Bewareof the glitter of highly reflecting material on the scene.
o Luminous or silver objects require a reflected and diffused lighting, possibly byemploying white screens.
o Antiglare spray is used to soften unwanted glitters.
o In order to make a scene with rain more visibile, a strong false light and a consistentcutting light is required; the same applies to snow, by slightly dimishing light intensity.
This article comes from Accademia della Luce - educazione alle tecniche della luce http://www.accademiadellaluce.it/article.php?sid=153

Source: http://www.accademiadellaluce.it/2010/PdfManualeTecnico_en/Cinematography.pdf