The Other Place wrote:
Not sure if there are flashes "designed to allow a longer duration..."

JSouthworth wrote:
.......And also some that are engineered for allow longer flash durations...

Remarkable insight, Cap'n!

Teila K Day Photography wrote:
The Broncolor MOVE pack and Broncolor Siros strobes were engineered to do just that, to EXTEND the flash duration even though Broncolor is known for their product having short flash durations.  This is when Broncolor used HS (hyper sync)  as opposed to HSS (high speed sync).  The difference is that HS uses a single flash with a relatively long flash duration, which can allow one to use faster shutter speeds beyond the manufacturer's published sync speed for a particular camera.  In contrast HSS uses fast pulses of light to SIMULATE a long flash duration for the same effect.   Each method has pros and cons.

**Broncolor has ditched HS and has gone with HSS in it's newer studio packs that debuted in the last quarter of 2023. The Satos packs, which give the photographer the ability to mix continuous temperature controlled lighting with temp. controlled flash... all from the same strobe unit for an endless breadth of artistic options whether using battery or mains power.

Thanks for that info!

I know that some have used old strobes at full power to enable faster focal plane shutter speeds with flash.  However, I did not know that a manufacturer actually tried to extend a single flash duration (as opposed to high speed sync).

JSouthworth wrote:
If you think about it, the X-sync speed of a focal plane shutter is also the time taken for each shutter curtain to traverse the film gate, and the total time required for the shutter to complete ANY exposure at speeds higher than the X-sync speed, when it is the width of the slit formed by the shutter curtains that varies, so if the X-sync is 1/250 then at 1/500 the slit will be 1/2 the width/height of the film gate, at 1/1000 1/4 the width and so on, because the speed of the shutter curtains is the same at all speeds. So if X-sync is 1/250 the flash duration will have to be at least 1/250 second to get even exposure at higher speeds BUT the flash has to begin before the first shutter curtain starts to move, not when it has exposed the entire film gate as in X-sync. So "dedication" between the camera and flash unit is necessary, the extra electronics adding to the cost.

2nd curtain sync means that the flash fires just before the second curtain starts to move at speeds lower than x-sync rather than when the first curtain clears the film gate.

Nobody spotted my mistake? The time taken for EACH shutter curtain to traverse the film gate is equal to the X-sync speed, so if this is 1/250 sec then although the exposure is 1/250, the curtains will be moving for 1/125 sec and at higher speeds, shorter times tending towards 1/250 sec but always slightly longer than that, because the second curtain follows slightly behind the first.

The exposure time should not be confused with the time taken by the shutter to complete the exposure. They are not the same with a focal plane shutter.