Profoto Pro-7b t0.1 Flash Duration

I measured the t0.1 Flash Duration of the Profoto Pro-7b pack using one Pro-7 head.

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All measurements were with Pro-7 head (not 7b head), and measured from 10% of maximum intensity to 10% of maximum intensity (t0.1)

I measured whole stops only (MAX -> -4 on the pack) .  Since you can use the pack at 1/2 power and 1/4 power, this gives 7 stops (1200J to 18.75J)

One measurement in ‘A’ Asymmetric is an outlier, and should be retaken.

Some Findings:

  • A in Asymmetric (A 1/2|B 1/4) is same as B with switch up (A 1/1 |B 1/2)
  • Use B outlet in Asymmetric mode (A 1/2|B 1/4) for shortest duration flashes @ 300J and below
  • Use A outlet in Asymmetric mode (A 1/2|B 1/4) or B outlet in Symmetric mode @ 600J
    Example: if you need 600J, put the head into ‘B’ and set dial to ‘max’ or put dial in ‘A’ and set switch down (A 1/2|B 1/4); light will be same but duration will be 1/833 instead of 1/425 when head is in ‘A’ and symmetric (switch up)
  • Profoto manual appears to be wrong in flash durations
  • Pro-7b appears to reduce flash output by reducing voltage on the capacitors, which causes flash duration to increase.
  • Fastest setting is B 1/4 setting at 150J (dial at -1 which is 1/4 of 600)
  • risetime of flash is much quicker than it was with Dynalite, possible because pack discharges a higher voltage?
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