Moving head
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When moving head (moving head), sometimes moving head called is called a floating multifunction spotlight from the theater and event technology. Moving heads can usually be swiveled around two axes and are equipped with a color changing system and, depending on the type, with gobos . The light emission can also be regulated in terms of brightness.
Head-moving headlights are related to scanners , but work a little differently. When headlights move, the head of the spotlight moves with the light source itself. With scanners, the light source is fixed and the light beam is deflected with the help of a movable mirror or a mirror roller.
Moving heads are used for concerts, TV productions, theater, fashion shows and of course discos. The invention of the moving head is attributed to Vari * Lite , the breakthrough of this technology came in 1981 with the Genesis Abacab world tour.
Connection and control
Moving heads are often supplied with power via a PowerCon or IEC connection . To control them, moving heads usually have 5-pin or, contrary to the norm, 3-pin XLR inputs and outputs in order to receive a DMX signal and to loop it through to the next device (regardless of type). Professional devices often also have an Ethernet socket that enables the DMX data to be transmitted using ArtNET. Some modern devices even have a radio receiver to receive wireless DMX signals via WiFi or other radio technology. Some devices, usually entry-level models, offer a stand-alone mode in which other devices of the same design can also be controlled (master / slave). Newer devices sometimes also offer control via the newer RDM protocol (Remote Device Management), which is essentially an improvement on the DMX-512 protocol. For controlled use, i.e. the headlights are controlled by an operator, the devices usually have to be controlled via a lighting console or DMX software. Additional products such as tracking transmitters can also be used to automatically target people in the room.
Bulbs
LED lamps are increasingly being used as light sources , often with the option of color mixing. This makes the color wheels obsolete. For this, you often have to cut back on mixed colors, which usually come out as pastel colors, and white. Only systems with RGBAW LEDs can reasonably be used as white light lamps. For older devices and new products, which mainly come from high price segments, gas discharge lamps such as HMI, MSR, MSD or xenon lamps are still used, as in most cases they offer a higher light output.
construction
A moving head consists of three assemblies:
- the base
- the arm or bracket (yoke)
- the head
This construction gives you a very high degree of freedom of movement, so that the light of the projector can be directed almost anywhere within the scope of its mechanical freedom of movement, depending on the location of the suspension or the installation.
base
Depending on the manufacturer, the base usually houses the power supply, DMX electronics and the drive mechanism for the arm that carries out the horizontal so-called pan movement (from Panorama). The first moving heads from the manufacturer Vari-lite had a central control module to which several lights were connected. However, all connections (operating voltage, DMX, fastening and safety rope) can be found in the base of current devices.
poor
The arm is the link between the base and the head and performs the horizontal rotation ( pan ). As a rule, it can be rotated by 540 ° relative to the base, but there are currently several devices on the market which can perform an endless rotary movement without a stop ( infinite pan ). The arm also contains the drive mechanism for the vertical movement of the head ( tilt ).
head
The head contains the actual projection unit of the moving head and houses the lamp, the color and gobo wheels, the effect filters and the optics. The head executes the "Tilt" swivel movement, mostly at a swivel angle of approx. 270 °.
Types
A distinction is made between the following types of devices: Wash-Light or Washer , Spot or Profiler and Beam .
- Wash light or washer
- Spot or Profiler
- Beam or "AirFX"
- Panel
Spot
The Spot , also known as Profiler, is a projection light that corresponds to the profile spotlight . They have a lens that enables sharp images to be projected. The beam of a spot has a sharp edge. Spots usually have one or more color wheels, one or more gobo wheels , effect wheels, zoom and focus. The color wheels are used to create different colors; different colored glass panes are swiveled into the beam path. If there are several color wheels, the colors can often be mixed. In the case of high-quality devices, a color mixing system based on subtractive color mixing (CMY) is also used. For this purpose, the basic colors, which are mounted on rotating color wheels, are built into the headlight. The colors become stronger and stronger in the course of the wheel, this enables a continuous color mixture. The gobo wheels swivel gobos into the beam path and can thus enable different shapes of the beam, including two-color images (black / light color). This enables the representation of many small rays with only one lamp or the projecting of symbols, logos or the like. Effect wheels are usually only available in devices from the high-priced segment; they can, for example, display "water" or "fire effects". The zoom is used to enable different exit angles of the light beam. The focus is used to make the light beam sharp or blurred. Profilers usually have a very fast mechanical shutter called a "shutter". In most cases, two mostly toothed sheet-metal blades are swiveled into the beam path. This unit is also used for strobe effects. Professional devices have motorized shutter slides that can be used to crop the beam. The use of LED light sources with the option of color mixing has so far not been very widespread with spot lamps, since the forced use of several LEDs brings about a color shift that is clearly visible in a projection.
Washlight
Washlights correspond to conventional Fresnel spotlights and have a Fresnel lens as the exit lens . Washlights have a fuzzy beam with soft edges. The exit angle is usually relatively wide, which is why washlights seldom create a focused beam, but rather illuminate a large area. When using hazers , this enables “coloring the air”. They are usually equipped with LED lamps, which can change their color flexibly and continuously. You can therefore usually display all colors of the RGB space. Washlights often have a movable lens to enable the light beam to exit at different angles. Gobos cannot be used with washlights because the lens cannot produce a beam that is sharp enough. With washlights, it is possible to omit the mechanical shutter unit, since the often used LED light sources are able to change their brightness suddenly. This method, known as an “electrical shutter”, enables the head to be built more compactly.
Beam
Beam spotlights are a mixture of spot and washlight. You have a microfresnel lens as the exit lens, i.e. a very finely graduated Fresnel lens. They allow the use of gobos, although the quality of the beam is too poor to allow a projection. The gobos only create an effect in the air, which is why the manufacturer Martin Professional markets some of its devices as "AirFX". Beam lamps are used exclusively to generate a beam of light in the air when using hazers .
Video panel
There are now a few models whose head has been replaced by an LED video panel. They are not used to illuminate a surface, to generate a beam of light or to generate "colored air", but rather to display video signals or graphics.
Similarities
With the exception of a few special devices, each device has a dimmer that enables the brightness of the light beam to be varied. Most devices use the shutter for this because the lamp cannot be dimmed (discharge lamp). Moving heads with an LED lamp as a base usually have an electronic dimmer ( pulse width modulation ). Moving heads are available in countless designs and in power classes from 150 W to over 2000 W electrical power.
Advantages and disadvantages
The advantage of the moving head is that, unlike the scanner, there is no loss of light because the light beams are not deflected. In addition, the radius of action is greater with moving heads. The disadvantage compared to the scanner is that a scanner can make much faster movements, since the mirror has a lower mass than the head that has to be moved. Another disadvantage is that moving heads are usually louder than scanners.
literature
- Frank Burghardt (Ed.): Lighting technology for beginners. Control your own light show professionally with DMX. Elektor-Verlag, Aachen 2009, ISBN 978-3-89576-188-1 .
- Michael Ebner: Lighting technology for stage and disco. A handbook for practitioners. Elektor-Verlag, Aachen 2001, ISBN 3-89576-108-7 .
- Michael Ebner: Lighting technology for stage and disco. A handbook for do-it-yourselfers. Elektor-Verlag, Aachen 1992, ISBN 3-928051-12-1 (6th edition, ibid 1996).
- Jens Mueller: Manual of lighting technology. Formulas, tables and practical knowledge. Know-how for film, television, theater, events and events. 3rd, updated and expanded edition. PPVMedien, Bergkirchen 2006, ISBN 3-937841-25-3 .