Originally posted by Vytautas Hello, guys
I have in mind a plan to override the sync speed limit of the K5 (and of any other camera, for that matter). Is that possible? Kind of.
I plan to use only one HSS flash (the cheapest available) on the camera as a kind of "master" flash. Then an optical slave which ignores the preflash (or preflashes) of the HSS flash on camera. This optical slave would fire my Radiopopper Jrx transmitter. Transmitter fires the receivers, connected not directly to the off camera flashes but to simple delay circuits (easy to find in google) to delay the CONSECUTIVE flash pulses of eight off camera flashes by about 0.0007 s, 0.0014 s, 0.0021 s and so on respectively so that the long joined flash "pulse" covers the whole 0.00556 s (1/180 s) curtain travel time and therefore the whole frame is exposed by eight consecutive flash pulses. That sounds complicated but in reality I do not see it so difficult. What is more, the eight off camera flashes can be whatever model. I intend to use eight Nikon SB-24 units. If each of them is set to about 1/2 power setting (1/2 power means about 1/1100 s (or) 0.0091 s flash duration - plenty enough for eight pulses to overlap and to cover the whole frame) than there is lots of power even for the HSS work.
Has anyone thought about it? Or even tried it?
I've tried something like this with what equipment I have (a bunch of Metz flashes, optical triggers). My flashes have the "servo" slave mode and like @maxfield_photo mentioned, the Metz 58 has a 1/125 t.1 time. A plain optical trigger doesn't work with the following method, due to the pre-flash related to PTTL and HSS. The main camera flash acts as the HSS trigger for the remote via the PTTL pre-flash.
Off camera HSS "overdrive/oversync" method:
- Set HSS capable flash mounted on camera in HSS mode, point flash head at remote flash (i.e. away from subject so it doesn't contribute to exposure)
- This allows camera to go faster than 1/180 sync speed (e.g. 1/250 for sure, 1/500 can work, up to 1/1000 seemed to work too, but this depends on ambient light, aperture, and off-camera flash-to-subject distance). Set camera to shutter speed desired for exposure.
- Set remote flash in manual servo slave mode at full power (1/1). Ensure that the slave sensor can "see" the master on-camera flash.
- Fire away!
The remote flash starts to fire after the first pre-flash sent by the master, and due to the long flash tail, it "covers" the entire exposure duration, since the shutter time is relatively short. I'm not sure where exactly on the tail the shutter opens/closes, but I haven't seen much difference in terms of "hot" areas, although I haven't done any scientific testing. Not straightforward or convenient but it works consistently. The main reason to do this is for the higher flash power of the remote vs. "true" HSS flash pulses that are much weaker output (so it's not for freezing motion).
Hope that makes sense.