Cotty, I can't say for sure how high speed synchro flash modes work.
My guess would be something like this for film cameras... Because the camera gets to 1/1,000 or 1/4,000 of a second exposure by using a narrower and narrower slit that travels across the face of the film (1st to 2nd shutter curtain distance), I would pulse the flash. Say I used 200 (or 2,000) pulses of flash in that 1/4,000 of a second. I could get about any exposure I wanted and the illumination would end up being even because I fired the flash when the slit was at the top of the film and at the bottom and everywhere in between. Kind of a strobe, but very fast. I wouldn't have to get the mechanical parts to be perfect, there could be some slop in when the flash started and ended. Just so long as the flash was pulsing when the slit first opened until it finally closed. Regards, Bob S. [EMAIL PROTECTED] writes: > So: the button is pressed, the mirror pops up, the pre-flash fires, the > exposure is read and calculated, any adjustments are made to the flash, > (then, crucially) the second flash fires and continues to fire while the > shutter opens, the exposure is made, the shutter closes, and finally the > second flash finishes. > > This is the only way that I can see how flash can be used with a speed, > say, of 1/1000th sec. So, I assume that for any given exposure with the > flash switched to high speed sync, the flash power must be reduced to > compensate for the necessary longer duration. > > If the normal flash duration is 1/15,000 sec (say) at X power, then in > high speed sync mode the flash duration must be increased to about > 1/200th sec (my normal flash sync speed) at Y power (which would be less > powerful I presume). This would then be able to cope with any exposure > faster than normal flash sync speed of the camera up to the fastest > shutter speed of the camera. I also presume this method will be that > employed by any camera/flash manufacturer. > > Anybody know if I'm still on track here, or have I hit a > patch of oil and heading for the scene of th accident?
