Triggers that can achieve HSS with studio strobes?

Discussion in 'Lighting Equipment' started by john_e|2, Dec 4, 2015.

  1. I just spoke to a rep at Paul Buff who said my Einsteins can achieve HSS with the pocket wizard.
    Are there any other triggers that will do the same thing?
     
  2. HSS is a very different flash mode, the flash itself has to know how to do the continuous burst. And it is dedicated, that is, it has to speak the same language as the camera controlling it.

    The Einstein does NOT do HSS.

    However, pocket wizard does what they call HyperSync, which can somewhat simulate HSS with many flash units (that do not do HSS). The flash is NOT continuous however, nor HSS, so there are limits.
     
  3. Thanks. that helps a lot.
     
  4. Actually, many studio strobes and "ordinary" speedlights will have a long enough flash duration for passable Focal-Plane (FP) synchronisation. IME, anything with a t~0.5 of 3mS or longer should work. HSS is just a fancy and confusing name for old-fashioned FP synch. Trouble is that most modern DSLRs don't offer a simple manual switch or socket for FP-synch.
    So the real trick is to force the camera into its FP synch mode. This is normally achieved by fitting a suitable speedlight (or speedlite) into the hotshoe and simply raising the shutter speed above the maximum X-synch speed.
    Radio triggers that offer FP or HSS synch will mimic the response of a camera manufacturer's hotshoe flash, and thereby fool the camera into going into FP synch mode. Difference being that the trigger signal from the camera then comes at the beginning of the first blind travel, rather than at the end of its travel as in X-synch. There's also usually a little bit of manipulation of the synch signal to correct for the radio trigger's inbuilt delay, which may be manually adjustable to tweak for best results.
    Anyhow, there are now a few radio trigger devices on the market that do the above trick, apart from PW's. Results for Godox, Elinchrom and YongNuo all popped up immediately after doing a quick Google search for HSS flash triggers.
     
  5. A big slow light "should work" in the proverbial sense that some may imagine it's good enough, but a flash pulse is not a constant light. There is an early quick peak, and then it starts trailing off to nothing for quite awhile, relatively. As the shutter slit travels across the frame, the light is decreasing. Even if t.5 matches up, that's still a one stop loss across the frame, not insignificant. And slow would seem to rule out the Einstein as best choice for this.

    But if used in sunlight, the sunlight does light the rest of the frame, and can sort of hide the light falloff, at least there is no dark band. And sunlight is the only imaginable place HSS could ever be a goal, we would be an idiot to use it indoors when a speedlight can run circles around it. But a big slow flash is simply not the same thing as HSS, which is in fact a constant light for the shutter travel duration (but at a reduced flash level).

    Some speedlights do actual HSS (with the proper matching camera), but power demands might require ganging a few them. Joe McNally has touted HSS, but not everyone seems to realize he puts three or four SB-910 in one umbrella.
     
  6. Wayne, even "HSS" capable speedlights (lites) don't give a constant light until their power is reduced to less than half. I've recorded the light output from several hotshoe flashes in their FP mode using a digital storage 'scope - see one example below. They all have a humped or otherwise uneven output if the power required is approaching their full capacity, and some revert to the classic exponential decay curve.
    All the above is pretty inconsequential, since the evenness of illumination across the frame appears visually fairly even. A one stop vignette towards the frame corners, as seen on many lenses at wider apertures, mostly goes unnoticed; and it seems the same is true for a linear vignette due to flash falloff. Of course you wouldn't want to copy flat artwork with such a setup, but for normal 3D subjects the "humpy" FP flash works OK in practise.
    The attached is a composite of graphs from an FP-mode flash at Full, Half, Quarter and Eighth output. As can be seen the light output versus time becomes more uneven as the required energy is increased. At full-power the flash gives up trying to do pulse-modulated output and simply exponentially discharges as normal. However, in everyday use that just doesn't show in the pictures.
    Incidentally, the lengthy flash duration of 7 milliseconds is very wasteful of energy compared to X-synch, but necessary to cover the transit + exposure time of a typical DSLR focal-plane shutter set to 1/500th of a second.
    00dclq-559646584.jpg
     
  7. Interesting graphs. What flash is that? My Nikon SB-800 HSS full power level certainly does not default to normal speedlight mode, but HSS is down about 2.3 stops from speedlight full power. I have another Chinese Aperlite YH-700 that does HSS well, but a Neewer NW-985 was a HSS joke.
    I assume your "less than half power" does mean less than half of the already reduced power mode that HSS flashes must use at HSS full power? But your full power comment confuses me.
    Your worst case graph shows a drop of average power to be slight, compares very favorably with the one full stop of a big slow flash at t.5 time. Average power shown about 3 units high, drops 0.5 unit instead of 1.5 units. And HSS does last full travel time.
    And again, both losses are a less drastic effect out in bright sun where HSS would be used. At least no dark bands.
     

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