English
- 17 -
4.3 Operating Modes
The ballast can be operated in three fundamentally different modes:
Low Noise
,
Flicker Free
and
High Speed
These modes can be selected by using the "F-Mode" button (see fig. 2, page
24). To change the operating mode the button must be pressed at least twice.
After the first operation, the LED of the actual mode starts flashing and thus
indicates that the operating mode can be changed now. The next push to
change the operating mode must take place within 2 seconds.
The ballast is switched to the selected mode only after the warm-up phase of
the lamp (about 3 minutes). During the warm-up phase, the lamp is always
operated in the "75 Hz
" mode. Moreover dimming of the lamp is deactivated
to allow the electronic detection of the power of the inserted lamp. The power
indicator LED next to the lamp connector is flashing to indicate the warm-up
phase.
1. Low Noise
When metal halide daylight lamps are operated flicker-free some noise may
occur, due to the special square-wave operation of the lamp.
In the position "50/60 Hz" (red LED indication) the noise will be substantially
reduced, the amount depending on the lamp, in some cases even to almost
zero.
The light, however, is
NOT
flicker free any more.
When operating in this mode, the same limitations for speed of camera
and/or shutter angle apply as for magnetic ballasts operated at 50 Hz (25
fps) or 60 Hz (30 fps). All other advantages of the electronic ballast will apply
as before!
The actual frequency is displayed at the LED display. The frequency can be
changed between 50 Hz and 60 Hz by holding down the "F-Mode" button for
about 5 seconds.
2. Flicker Free
In the position "75 Hz
" (green LED indication), the electronic ballast will
operate flicker-free. The metal halide lamp is operated at 75 Hz square-wave
current and gives out a constant light.
This mode is designed for flicker-free operation at standard film speed (25
fps / 30 fps).
3. High Speed
In the "High Speed" positions (white LED indications) the electronic ballast
will operate flicker free in high-speed mode. The metal halide lamp is
operated at about 300 or 1000 Hz square wave current and gives out a
constant light.
This mode is specially designed to achieve high resolution pictures when
using digital cameras with high frame rates.
With some lamp types resonance phenomena can cause visible instabilities
of the arc when operated at 300 and 1000 Hz. Variation of the output
frequency avoids this resonance phenomenon and stabilizes the arc.
The High Speed
frequency range can be set for 300 Hz (270
– 360 Hz) or
for 1000 Hz (900
– 1200 Hz). The setting can be changed by pressing the F-
mode button for a longer time (approx. 5 seconds)
during operation in
"MAN" mode
. Switching can only be performed
after the warm-up phase
is finished and the frequency display no longer indicates 75 Hz but the
selected high-speed frequency.
