I often, of course, say this – “Limit: when using flash, you cannot exceed your camera’s fastest sync speed (usually 1/250th second)”.
And then almost as often, I hear the following objection:
“But Michael: you can use High Speed/Auto FP flash!”
And that way, you can exceed the sync speed. Sure – like in this photo of Aurèle Monfils of the Porcupine Photo Club, which I made yesterday with the standard sunny day blurred background setting (write it down!) of:
- 100 ISO
- 1/2000th sec
…using an on-camera flash fitted with a Honl 8″ Traveller 8 softbox:
Yes. You can, as you see!
But now I have a “but”.
The high-speed mode works by effectively making your flash into a continuous light, at least for the duration of the shutter speed; it flashes pulses at 40 kHz. Fine, but most of those pulses reach the closed part of the shutter, so most energy is wasted; hence, your effective range is reduced dramatically. Maybe just over a metre at 1/2000th second when using the flash without modifier; with a softbox as I was using here, maybe 30cm, no more.
Hence the slight “wide angle” look in my image above due to me having to be close, with a wide lens. As in this one of Aurèle’s daughter Lisa:
So while it is true that high speed/FP flash solves the sync speed problem, it’s not a panacea, and in practice, it is only occasionally usable.
Footnote: Lisa is turned away from the sun: It is behind her, meaning she is not squinting, and the sun becomes the shampooey goodness™ light on her hair!
Want to learn to use modern Flash technique? I travel worldwide for hands-on seminars. Vegas, London, the Netherlands, Phoenix, Niagara, Toronto, or Timmins: wherever you want me, I’ll be there for you.