hne said:
HSS works by extending flash duration and HS works by chopping it.
Not quite. Both try to make the flash emit light for as long as the shutter blades travel.
The light time needed is always one third stop longer than the max x-sync speed.
The shutter blades always travel at the same speed, no matter if you shoot at
30 seconds or 1/8000 seconds exposure time. The difference is the gap between
the two. At X-sync, the gap is exactly as wide as the frame.
One stop shorter, and the gap is only half as wide, so half the flash light
does not reach the sensor but instead is wasted on the shutter blades.
This counts for both HSS and Hypersync (and it's copies).
Select another stop shorter, and the shutter gap is halfed again,
and again the light is burnt on the shutter blades but does not
reach the sensor. And so on. No matter if you use HSS or Hypersync,
both burn the majority of light onto the shutter blades. Period.
The Elinchrom marketing claim is badly misleading, to say the least.
hne said:
When you turn on HSS you lose a stop, give or take.
The same counts for Hypersync. Simply activating either of the two means
that the flash starts emitting light before the shutter blades start, and still
lights a small time after the shutter has closed again.
This extra preroll and postroll time cannot be used for the exposure, for
both techniques.
On top of that every stop shorter in shutter speed halves the gap between
shutter blades compared to a longer stop and thus kills another stop.
Both HSS and Hypersync are workarounds that will die when global shutters
become available for flash sync as well.
hne said:
HS (or SuperSync, HyperSync, ...)
(...)
The shorter shutter speed you use with HS, the smaller the part of the flash output curve you use.
No. You don't chop anything out. The flash fires free until the minimum discharge
voltage of the capacitor is reached and the plasma in the flash tube dies.
hne said:
HSS and HS give exactly the same possibilities of stopping fast motion, since they
both make a flash behave like a continuous light source.
That is correct.