General information, optic specifications, index

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L956D957_SRC.QXD 11-03-2004 08:22 Pagina 12.18 Information – Lighting technique 1. Noticeable visual effect (Factor 2:1). 2. Low theatrical effect (Factor 5:1). 3. Theatrical effect (Factor 15:1). 4. Dramatic effect (Factor 30:1). Can only be achieved with relatively low general lighting levels. 5. Very dramatic effect (Factor 50:1). Can only be achieved with relatively low general lighting levels. 12.18 GENERAL INFORMATION, OPTIC SPECIFICATIONS, INDEX Accent factor The visual effect when highlighting an object is determined by two things: the contrast between the object and its surrounding background, this is called contrast; and, the shadow effects in the object itself caused by the form of object and the position of the spotlight, this is called modelling.The main lighting characteristics of light sources to achieve the required contrast are the size and the sharpness of the contour of the visual beam. In a first approximation, the contrast between an object lit by a projector and its surrounding background is given by the ratio Eobject/Ebackground. In most diffuse general lighting schemes, Ebackground is closely related to Ehorizontal.When planning accent lighting, it is important to determine the required effect or accent factor, which may vary from ‘noticeable’ to ‘very dramatic’.The issue is the relationship between the amount of general lighting in the direct vicinity of the object and the brightness of the spot on the object. It is calculated by dividing the lighting level in the spot by the general lighting level in the horizontal plane, approximately 1 metre above the floor in the direct vicinity of the object. Lighting level in the spot (on illuminated object) Accent factor = <strong>General</strong> lighting level (horizontal plane) To obtain satisfactory effects in situations where the level of general lighting is high, powerful accent lighting should be used. Figure Accent factor Effect 1 2:1 Noticeable 2 5:1 Low theatrical 3 15:1 Theatrical 4 30:1 Dramatic 5 50:1 Very dramatic
L956D957_SRC.QXD 11-03-2004 08:23 Pagina 12.19 K1 is a profile spot without any spill light; this effect is achieved by equipping the luminaire with a mechanical or <strong>optic</strong>al device that cuts off the spill light; in this way, beams of different shapes can be produced. This classification can have high- or low-intensity beams, depending on the power and efficiency of the system. K2 is a spot which stands out due to its sharp shift to a minimal amount of spill light; this type of beam is excellent for creating theatrical and dramatic effects. This classification is usually associated with very high-intensity beams. K3 has a hard shift from a highintensity spot to spill light; the spill light is seen as a narrow ring of light around the spot. This classification is usually associated with high-intensity beams which are very suitable for creating theatrical effects. K4 has a soft shift from a relatively strong spot to a great deal of spill light; the spill light assists considerably in lighting the general surroundings. K5 is a uniformly wide beam without any visible spot and is, as a result, suited to general or supplementary lighting. Beam characteristics – K-beam categories Accent lighting requires a controlled beam of light, obtained by a lamp and a reflector, which in many cases is integrated into the lamp itself.The ultimate effect is largely determined by the characteristics of the beam.The important factors are the intensity, the shape and the dimensions of the spotlight created by the beam and the amount of spill light. Spill light is the amount of light that is allowed to spread outside the actual beam. A 'hard-edged' beam is a light beam with little or no spill light and gives a sharply defined contrast. It lends itself to very dramatic lighting effects. A 'soft-edged' beam has a higher degree of spill light and will result in a lower contrast with the surrounding area.The effects are much softer than those obtained with a hard-edged beam.To help you make the right selection, Philips has a special classification for its reflector lamps and lamp/reflector combinations, identifying five socalled K-beam factors.The final effect is, of course, influenced by the contrast between the ambient lighting and the lighting intensity of the beam. Identifying the five K-beam categories The illustrations here give a good impression of the effects of the various types of light beams identified by the Philips K-beam classification.The relevant light beam creates these effects only, without any supplementary lighting. GENERAL INFORMATION, OPTIC SPECIFICATIONS, INDEX 12.19
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