Godfrey DiGiorgi wrote: > For effective second curtain sync actuation, all that is required is > that the camera send a trigger signal to the flash at most .004 > (1/250) second before the second curtain is released for its closing > run. That's the typical longest electronic flash duration of a > professional studio flash. > > Nothing 'smart' is necessary in the flash at all. > > Godfrey
Absolutely true. It used to be done mechnically from the camera body with a second set of contacts interacting with the closing curtain. This, of course, required the extra contacts and a switch to use them. Digital flashes can obtain the information from the (robo)camera. This, of course, requires the programme in both units to be able to make sense of the photographer's desires. Sometimes, I feel this is where digital lets us down. > > On Oct 13, 2007, at 7:25 PM, Rick Womer wrote: > > >>I'm not sure you're right... >> >>For effective second curtain synch, the flash needs to >>fire =immediately= before the shutter closes. A >>non-dedicated flash gets a signal at some point when >>the flash is fully open, but does not know exactly >>when the flash opened, or when it will close. For >>second-curtain synch, the flash either needs to know >>when the flash opened and the shutter speed, or needs >>to get a signal a millisecond or so before the curtain >>starts to close. Those are easily encoded so that >>only a dedicated flash "knows", it would seem. > > > -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
