TPB #48 – Flash Duration Verification

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This video goes over the Flash Test Menu and finds why it hasn’t been reporting correct flash durations. The problem turned out to be the light sensor being used is not fast enough. To make this mode work reliably we’ll need a new light sensor that quickly transitions from <1V to >4V. I estimate a responce time of less then 5 us would be good for standard flashes and less than 0.1 us for air-gap flashes.

Beta version of Camera Axe software with Flash Test Menu


About the Author:

Maurice is a computer engineer, photographer, and all around renaissance man.


  1. alan sailer  July 6, 2012


    It is puzzling that the phototransistor is giving such bad results. I have not worked with them much, but maybe the unit is saturating because it is so close to the flash, thus keeping it on after the flash has gone dark.

    To test this it would be interesting to measure the strobe in a dark room and to vary the distance from the strobe to the detector. If my theory has any validity, the pulse measurement should get shorter.


  2. Koby┬áRennie  July 13, 2012

    Well Done Maurice….
    Impressive Work…
    Keep going mate.