Originally posted by stevebrot
1 cycle = 0.017s for 60Hz or 0.020s for 50Hz*.
According to the Canon link, it only works on lights that are 100Hz or 120Hz, so the delay may be even less. These are common flicker frequencies for fluorescents, due to the physics magic that happens inside the ballasts for the lights (I may have understood it 20 years ago, but now I'll call it magic

).
The delay of my trigger finger is an order of magnitude larger than the shutter lag of most dslr's

, but it would definitely be interesting to know if the added delay is noticeable in real use. Not being a predictable delay may set off the ultra skilled action photographers. Given that Canon's default is to have it disabled, I'd bet that either the delay or lowered fps is noticeable or at least easy enough to measure and that Canon users are just as froth prone as Pentax users about these things