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Projection lamps Han Fokkelman

In the beginning there was no electric light so the picture of the
‘Magic Lantern’, originally ‘Lanterna Magica’, had to be project-
ed by means of candles or oil lamps. When the electric lamp
appeared it was used at once but it was difficult to get a good
picture. The filament was circular and, as the lamp was placed
horizontally, good projection was difficult. Further, the name of
the bulb had to be on the bottom of the lamp otherwise you could
read the printing on the projected image.

Soon special projection lamps were designed.
They had to give more light than a normal lamp
and that meant a shorter life. The filament wire
was folded in a network to give more light to the
projection surface of the commonly used 8.3 × 8.3
cm slide. As the wire expanded when it was lit,
you had to place the lamp in the right position.
Therefore you read: Top or Oben (German) or
Boven (Dutch) on the lamp.
Fig 1. A selection of projection lamps
The lamp was general-
ly sited horizontally but, in episcope and
epidiascope projectors, some lamps were at
45º. Another system was the hanging lamp,
which you can find in some ICA projectors.

Most lamps had an E27 screw base, but you
can also find projectors that needed an E40:
the ‘Goliath’ base.

It was time for standardization. The result
was a standing lamp with a vertical fila-
Fig 2. Lamp with word ment. The distance from the heart of the Fig 3. Hanging Lamp.
“Boven”. filament to the base was standardized to
55.6 mm. The lamp gave more light than a normal
lamp so it had a shorter life and the standard
became 25–40 hrs. The base became the P28 that
had two different wings so you could only place
the lamp in the right position. They were delivered
for 110 Volts and 220 Volts in different wattages.
But with more watts you got more heat: you
couldn’t win! Heat became the enemy of the pro-
jector manufacturers and, as a result, they pro-
duced slide projectors without motor cooling up
Fig 4. E40 and E27 screw to 250 Watts, but for 300 Watts and more a
bases cooling fan was necessary. Fig 5. The P28 base.