Mark, what you experienced is one of the reasons I don't recommend folks try that popup flash triggering hack. The other of course is the light pollution from the popup flash getting into the shot and flattening the contrast.
But you have at least two possible issues with each student's camera: the x-TTL pre-flash, and the "red eye reduction" pre-flash. Either or both of these might be enabled in any given camera. The xTTL preflash is usually enabled even if manual exposure is in use because of the possibility for remote flash control. I used to use that feature with the K20D and the K-3 as a poor man's remote trigger. No danger of the popup flash appearing in the shot because it doesn't fire when the shutter is open. But it only works with flashes that support a pre-flash -- manufacturer dependent timing -- and some newer Chinese strobes that can be set to ignore 1-n pre-flashes. BTW, most PCB strobes come with a really long old-school PC-Sync cable. That might have helped with any of the students cameras that have a sync socket. -- -bmw -- 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.
