On Sun, 12 Dec 2004 00:11:43 +1100, Kevin Waterson wrote: >This one time, at band camp, Bob Sullivan <[EMAIL PROTECTED]> wrote: > >> Take a picture of an object moving 60 miles per hour. Calculate flash >> duration based on the motion blurr you see...if you find any. >> Regards, Bob S. > >I need a flash duration of between 1/15,000 and 1/20,000 and I need lots of >light so simply reducing the power on a small flash wont do it. I wondered >if there was any way to measure the duration of various flashes.
Kevin Full power on most flashes is a duration of 1/500 sec. Flash tubes only have one level of brightness and vary light by adjusting the time it is on. So 1/20,000 will be 1/40 of full power (quite close to min power). 1/32 of full power will give you about 1/16,000 sec. For the shortest duration the best you will be able to do is get a whopping big flash and set it for low power. the good news is that you should easily be able to calculate exactly how much light you will get from a flash at that power level. Leon http://www.bluering.org.au http://www.bluering.org.au/leon
