Thorn Compact Iodide Daylight CID Lamp
The CSI and CID compact source lamps from Thorn Lighting proved extremely popular in the professional studio lighting business during the 1970s and 1980s, primarily on account of their very compact dimensions by comparison with the alternative state of the art. Such types of compact source lamp were traditionally always made in the double ended format, which resulted in large lamps that were not so easy to mount in an optical system.

Thorn, or rather its predecessor AEI-Mazda, was responsible for developing the first single ended metal halide arc tubes with only one pinch-seal. The first lamp in the family was the 400W Compact Source Iodide (CSI), developed primarily as a technical light source for special projection. A 1000W version soon followed, which was widely employed in floodlighting applications. A very narrow and tightly controlled beam was attainable on account of the small arc and the ease with which it could be mounted in a reflector.

A later development was the Compact Iodide Daylight CID lamp in 575W and 1000W. These competed with the double ended HMI and MEI types of Osram, delivering a similarly high daylight colour temperature. Colour rendering suffered slightly owing to Thorn's preference for the indium-tin halide system, which was inferior to the Osram rare earth system.

This 200W lamp is the smallest in the family, developed for battery-powered outdoor filming. The ignition voltage is lowered by means of the auxiliary external electrode connected to a mica plate capacitor in the base. To enable hot-restriking, two quartz insulator legs are sealed to the arc tube pinch with a low melting temperature solder glass.
Manufacturer: Thorn Lighting Ltd. Lamp Ref. 99-0211
Lamp Power: 200 Watts
Lamp Current: 3.3 Amps
Lamp Voltage: 70 Volts
Cap Type: GY9.5 Hot Restrike Variant
Bulb Type: T-14 T-3.5 in eighths/inch
Bulb Finish: Clear Quartz
Electrodes: Tungsten Single coil
Arc Length: 5 mm 6/32 inch
Atmosphere: Ar | Hg (Sn,In)Ix
Luminous Flux: 14,000 lm (@ 100 hrs)
Luminous Efficacy: 70 lm/W (@ 100 hrs)
Colour Temperature & CRI: CCT: 5500K CRI: Ra 80
Chromaticity Co-ordinates: CCx: 0.333 CCy: 0.341
Rated Lifetime: 100 hours
Warm-up & Re-strike Time: 1 minute 15 minutes
Burning Position: Universal
Overall Length: 57 mm 21/4 inches
Light Centre Length: 36.5 ± 1 mm 1.43 inches
Factory: Leicester England
Date of Manufacture: August 1988 Date Code: 80
Original / Present Value: GB £106.04 (1988) GB £253.90 (2014)