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| p.1 #7 · ~1/200th limit with bees/cybersyncs |
RoadconePhoto wrote: so, which part is the limitation... supposedly the cybersyncs trigger in like 1/4000th of a sec and the bee fully discharges in something ike 1/4100th... yet anything over 1/200th will outrun the strobe.
As stated above, the problem lies with the way shutters work.
At or below the maximum sync speed -- whether that be 1/250, 1/200, 1/125, or whatever -- the first curtain fully opens, exposing the sensor, then the flash fires its very brief pulse, then the second curtain closes, covering the sensor. A faster shutter speed doesn't mean that the curtains are moving faster, only that the delay between first curtain opening and second curtain closing is shorter.
But above sync speed, the curtains can't move fast enough to do the job, so instead the second curtain starts to close before the first curtain is fully open, creating a moving slit that "wipes" across the sensor, exposing any given part of the sensor for the correct time for the shutter speed set.
That works great in sunlight or continuous artificial light, but when using flash it doesn't; the brief burst of light from the flash will only hit the part of the sensor that's under the slit at the moment it fires.
Trigger latency can be an issue when operating just a bit above sync speed, because sometimes slow-acting strobes can be timed to fire in such a way that they stay at a relatively steady brightness as the curtains move across the sensor, but only if the timing is precise and usually only at low power settings with voltage-controlled strobes. Speedlites and IGBT/thyristor-controlled strobes work differently, and lower power settings will actually shorten the flash duration, making out of sync shutter speeds worse instead of better.
There are a few ways to get around the sync speed issue. The two most common are use of leaf-shutter lenses that can open and close at speeds of 1/500 to -- in the newest models -- 1/1600, or the use of High Speed Sync (Canon's term), Focal Plane Flash (Nikon's term), or other similar methods, where the Speedlite/Speedlight/flash gun is fired multple times in short succession (at vastly reduced power) to simulate continuous light during the entire shutter travel.
Some point and shoot cameras, and a few DSLRs, use an electronic "shutter" rather than an actual physical shutter, and they don't have the same sync speed issues because the sensor is always exposed; the sensor is just switched on and off electronically to simulate a given shutter speed. There are also "hybrid" designs that only have one curtain. Both of those systems have other issues, though, which is why most DSLRs still use a traditional mechanical shutter.
Lot's of info here, but hopefully it helps or at least points you in the right direction for further reading.