Total spectral energy distribution of typical
studio lamp
| 100 |
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| 80 |
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| 60 |
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| 4 | 0 | 0 | K |
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relative energy | 20 |
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| 300 | 400 | 500 |
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| 600 | 700 | 800 |
wavelength (nm)
Spectral energy distribution can be shown in absolute terms whereas radiation in terms of visible light is related to the response of the human eye. (Spectral distribution chart on previous page)
Operating Temperature of Tungsten Halogen
Studio Lamps
The following maximum and minimum temperatures are suggested for optimum life. Operation outside these figures will not necessarily cause immediate failure but will affect life adversely to an increasing extent.
Seal - 450°C maximum
Above this figure the sealing foil oxidises at a rate increasing with temperature and is frequently the cause of short life due to seal failure.
Bulb - 250° - 800°C
Outside this range the halogen cycle becomes less efficient and blackening may occur. Temperatures above 1200°C will cause the bulb to soften.
Pins - 350°C maximum
Above this figure the plating on the pins may lose adhesion and the contact will deteriorate. Such deterioration may form local hot spots which rapidly worsen and may result in arcing and irrepairable damage to both lamp and holder. Should signs of this be evident on removal of a failed lamp, it is important that a good contact is restored by replacing the lampholder before the next lamp is fitted. Otherwise the new lamp will rapidly fail in a similar manner.