Thoughts on Trailing Curtain Sync
pnstenquist at comcast.net
Fri Jul 2 21:21:07 EDT 2010
On Jul 2, 2010, at 7:05 PM, Adam Maas wrote:
> On Fri, Jul 2, 2010 at 4:53 PM, John Sessoms <jsessoms002 at nc.rr.com> wrote:
>> The K-10D and K-20D both allow you to set the on-board flash to trailing
>> curtain sync. How difficult would it be for them to make the hot-shoe also
>> fire on the trailing curtain when a non-dedicated "flash" is installed?
> Very difficult unless certain assumptions about burn time are made,
> which won't be accurate. You need to fire the flash at just about
> exactly the burn time before the shutter closes for trailing curtain
> to work corectly. Most speedlights have a roughly 1ms full-power burn,
> but at low power levels it can be an order of magnitude shorter as
> output is normally controlled by burn duration rather than intensity.
> Olympus did allow this on some OM models, but it only worked because
> of the low sync speed of the camera's (1/60) so that even if the flash
> burn time was much shorter than the assumed ~1ms you don't get much
> exposure after the burn ends. This doesn't work so well with today's
> high sync speeds.
Of course you can shoot trailing curtain synch at low shutter speeds on either the K10 or the K20. I get good results shooting trailing synch on the K10, K20 and K7 at 1/8th or 1/15th.
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