[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?

[Johnyb3000]

Chuck, if your maximum (non-HSS) flash speed is 1/160, it means you have your camera configured to use 1/3 stop increments. Switch to the more traditional 1/2 stop increments and you'll see a max flash speed of 1/180.

The difference between 1/3 and 1/2 stop steps is at most +/- 1/6 stop. Few exposures are going to be critical enough that you can't deal with that in processing.

You are the man!!!!

[maxfield_photo]

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 used my Cactus V5s to both fire my camera and my flashes at speeds over 1/180th. I was hoping to "hypersync" by using the flashes at full power and capturing the tail, but there is a problem with the timing, and the frame is completely dark. I think the shutter is firing just prior to the flash. We're talking milliseconds difference, maybe less. Perhaps the delay circuit you mentioned can solve my problem.

However, if you have eight flashes at your disposal, why not either stop the lens way down, OR get a heavy duty ND filter, and just fire them all together using brute force to overpower the ambient light? Your subject didn't need those retinas, right?

[Vytautas]

It is not possible to fire both camera and flashes with a radio receiver. Firing camera is one thing. This will not be synced with the movement of curtains. I also doubt the delay circuit can solve this.
What the delay circuit can do is only to fire several flashes at constant intervals to overlap and to cover the whole time of curtain travel to light the whole sensor (the more frequent the flash pulses, the more even the lighting.)

Stopping the lens down is not an option for portrait photography on sunny days, when shallow depth of field is needed, which is my main purpose.
Heavy ND filters are a good option and I like to use them often, but there is one big BUT - they kill auto focusing and make manual focusing extremely difficult.

[demp10]

Given that the t1 time for most flashes in full power is in the range 1/500 to 1/1000, firing both the camera and the flash with external means (e.g. remote triggers, etc.) should work. Adding a delay unit to the flash trigger signal, will allow fine tuning down to the msec. One issue though will be exposure consistency. The flash output is not linear; it goes up very quickly and then decays gradually. At high speed, the shutter is not fully open, so each section will be exposed at different levels that may be several stops apart.

Perhaps at very high shutter speeds (over 1/1000) and with careful delay timing to get the peak of the flash output, the difference will be small.

I have a trigger delay device to photograph water droplets (which works great) so I'll give it a try when I have some time and see if it will work with high speed shutter.

[maxfield_photo]

Actually the t.1 time on my Metz 58 is published as 1/125th, and I suspect my Metz 45CL-4 is longer than that. The trick is not to capture the peak though, that will produce a "hot side" and a "cool side" to the image. Ideally the curtains should start moving 1/180th of a second before the end of the tail to produce the most even illumination across the frame. It's like the old flashbulb timings.

[Lowell Goudge]

Something no one has mentioned yet, but the *istD can do HSS with the body flash, and use the body flash as the master for off camera HSS with the second flash

[Vytautas]

Given that the t1 time for most flashes in full power is in the range 1/500 to 1/1000, firing both the camera and the flash with external means (e.g. remote triggers, etc.) should work. Adding a delay unit to the flash trigger signal, will allow fine tuning down to the msec. One issue though will be exposure consistency. The flash output is not linear; it goes up very quickly and then decays gradually. At high speed, the shutter is not fully open, so each section will be exposed at different levels that may be several stops apart.

Perhaps at very high shutter speeds (over 1/1000) and with careful delay timing to get the peak of the flash output, the difference will be small.

I have a trigger delay device to photograph water droplets (which works great) so I'll give it a try when I have some time and see if it will work with high speed shutter.

Good.

When you have a chance, please, test it. Then I will now if it is at viable to try.

[Lowell Goudge]

Given that the t1 time for most flashes in full power is in the range 1/500 to 1/1000, firing both the camera and the flash with external means (e.g. remote triggers, etc.) should work. Adding a delay unit to the flash trigger signal, will allow fine tuning down to the msec. One issue though will be exposure consistency. The flash output is not linear; it goes up very quickly and then decays gradually. At high speed, the shutter is not fully open, so each section will be exposed at different levels that may be several stops apart.

correct

Perhaps at very high shutter speeds (over 1/1000) and with careful delay timing to get the peak of the flash output, the difference will be small.

actually no the difference will be more defined because what changes with higher shutter speeds is not the sweep speed of the blades, but the width of the slit, therefore at moderate speeds above sync the slit is likely 1/4 to 1/3 of the frame, so the light hitting any one part is going to be there longer, but at extreme speeds the slit could be only 1-2mm wide, therefore the time along the flash discharge curve will be very short for each section of sensor/film, and as a result more susceptible to the variations along the discharge curve

I have a trigger delay device to photograph water droplets (which works great) so I'll give it a try when I have some time and see if it will work with high speed shutter.

it should but you will need to use only full power, and even then, the real issue is that when you consider 1/180 sync speed, this also leads to an implication that the actual sweep time of the blades is somewhere in the 1/200 of a second range, and the flash duration, even at full power, may not be long enough to cover this time. this is likely why high speed sync is multiple pulses, because the maximum duration of the flash is shorter than the full frame sweep time of the shutter blades

[Vytautas]

One flash will not be enough. What is needed, is several flashes (eight is enough for 1/180 s) and a separate delay circuit for each flash. The delay would have to be precisely tuned so that each flash fires at 0.0007 s intervals consecutively (1/2 power setting enough). The lighting should be quite even throughout the whole frame as each flash fires at the moment when the pulse from a previous flash is still strong.

[thigmo]

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.

[thigmo]

I've used my Cactus V5s to both fire my camera and my flashes at speeds over 1/180th. I was hoping to "hypersync" by using the flashes at full power and capturing the tail, but there is a problem with the timing, and the frame is completely dark. I think the shutter is firing just prior to the flash. We're talking milliseconds difference, maybe less. Perhaps the delay circuit you mentioned can solve my problem.

I have V5 transceivers as well, and have used them to trigger a remote camera. The problem is that there is definitely a delay to the triggers that doesn't seem consistent. So I haven't been able to reliably sync a flash and a camera beyond 1/180, even though I have had it work on occasion. (i.e. remote flash on a V5, remote camera at e.g. 1/500 connected to a V5, and a third V5 to trigger the shot)