I've been researching lightning effects for work (I design power supplies for aircraft). I ran across an interesting table that could shed some light on capturing lightning during daylight hours. As most know, leaving the shutter open for a while at night can capture displays. I have taken a few like that but really want to get some during the daylight or twilight hours.
MIL-HDBK-419A
Table 3-1
Range of Values for Lightning Parameters (3-5)
Parameter Minimum Typical Maximum
Number of return strokes per flash 1 2 to 4 26
Duration of flash(s) 0.03 0.2 2
Time between strokes (ms) 3 40 to 60 100
Peak current per return stroke (kA) 1 10 to 20 250
Charge per flash (C) 1 15 to 20 400
Time to peak current (µs) <0.5 1.5 to 2 30
Rate of rise (kA/µs) <1 20 210
Time to half-value (µs) 10 40 to 50 250
Duration of continuing current (ms) 50 150 500
Peak continuing current (A) 30 150 1600
Charge in continuing current (C) 3 25 330
Note the duration of flash, typically 0.2 seconds. I would interpret that to mean that 50% of them would be 0.2 seconds or longer. If the shutter latency is less than that it should be possible to detect the flash 50% of the time. That could be done optically (photo diode trigger similar to flash slave only more sensitive) or electrically using a low frequency antenna and detector. The shutter speed could be adjusted to properly expose the ambient scene or possibly less for various effects.
A camera with electronic shutter (wired remote, not mechanical) would be required. Also the mirror locked up and possibly the aperture preset might reduce the latency.
Does anyone have any comments?
MIL-HDBK-419A
Table 3-1
Range of Values for Lightning Parameters (3-5)
Parameter Minimum Typical Maximum
Number of return strokes per flash 1 2 to 4 26
Duration of flash(s) 0.03 0.2 2
Time between strokes (ms) 3 40 to 60 100
Peak current per return stroke (kA) 1 10 to 20 250
Charge per flash (C) 1 15 to 20 400
Time to peak current (µs) <0.5 1.5 to 2 30
Rate of rise (kA/µs) <1 20 210
Time to half-value (µs) 10 40 to 50 250
Duration of continuing current (ms) 50 150 500
Peak continuing current (A) 30 150 1600
Charge in continuing current (C) 3 25 330
Note the duration of flash, typically 0.2 seconds. I would interpret that to mean that 50% of them would be 0.2 seconds or longer. If the shutter latency is less than that it should be possible to detect the flash 50% of the time. That could be done optically (photo diode trigger similar to flash slave only more sensitive) or electrically using a low frequency antenna and detector. The shutter speed could be adjusted to properly expose the ambient scene or possibly less for various effects.
A camera with electronic shutter (wired remote, not mechanical) would be required. Also the mirror locked up and possibly the aperture preset might reduce the latency.
Does anyone have any comments?
