[EMAIL PROTECTED] wrote: > On Dec 24, 2006, at 7:23 PM, Gonz wrote: > > >>I would imagine that since the flash is very fast, probably faster >>than >>1/10000 of a sec, that you could wait right up until the second >>curtain >>started to close. So if you did this, it would be closer to >>1/500th of >>a sec before the second curtain closes, assuming the first and second >>take equal time to traverse the frame and the sync time is 1/250th. I >>suppose you could experiment with the shutter speed, i.e. try 1/125th >>and 1/250th + second curtain sync to see where the time actually is >>for >>the flash. > > > If the system is very very sophisticated and can incorporate the > timings for a flash quench dynamically, yes, the flash could fire at > as little as the minimum quench time it is capable of. But most > second curtain timings are set for about 1/250 second prior to second > curtain release because that is the average usual flash illumination > time for a studio electronic flash at full output. >
That would mean that if you did this, then if the flash sync speed was 1/250th, and you set the flash to second curtain sync, and you had your shutter set to 1/250th, then it would not work, because 1/250th before the *second* curtain *release* was when the first curtain started to release, i.e. the sensor was still not exposed. Maybe you meant 1/250th before the second curtain closed, i.e. right when the second curtain was about to be released. This would make sense. In that case, at this speed, its equivalent to a regular first curtain sync flash. > Of course, this speculation and trivia is irrelevant to practical use > of second curtain sync or the initial question. > > Godfrey > > -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
