Did some product shots today with the studio lighting kit I got recently and the camera (DP3M) appeared to sync with the strobes at pretty well any shutter speed and aperture combination I chose ... which certainly makes the whole process very easy!
Why are leaf shutters so superior when syncing with a flash?
Most of the answer is in this thread already ... summing up:
Ignoring long-burn FP (stands for "focal plane") flash bulbs and "high speed sync" mode electronic flash (essentially the same thing as FP bulbs implemented with an electronic flash), the primary difference between a leaf shutter and a focal plane shutter is that a leaf shutter's operation achieves all the leaves at the wide open state for every exposure time. A focal plane shutter only achieves this state for a range of timings up to a limit imposed by the speed at which the shutter curtains travel across the film plane.
When using electronic flash, the duration of the flash burst can range from 1/250 sec to about 1/12,000 sec. The concept of
X flash sync means firing the flash such that the entire burst of light is timed to happen within the time when the shutter is fully open so as to get even illumination across the entire frame.
A leaf shutter's fully open state happens at all shutter speeds so they can theoretically sync at all shutter timings. However, with fast lenses the fully open state can become shorter than the duration of the electronic flash with a powerful or long-burning flash unit (film or digital, it doesn't matter). This causes a fall off in illumination around the edges of the entire frame when it happens, but the whole frame gets exposed. The true sync limit is the speed at which the blades can cycle. Few leaf shutters achieve shorter exposure timings than 1/500 second (unassisted by sensor cut-off and other tricks) and there are also few leaf-shutter lenses of large enough diameter such that the fully open state cut-off is compromised, so in general you can always think of a leaf shutter as being able to sync at any speed.
A focal plane shutter has two timing modes: the first when the total exposure setting will mean that the shutter can achieve the fully open state and the second when the total exposure setting will mean a slit opening traveling across the film plane. Total exposure for ambient light is the integral over time that the shutter curtains are open over each instantaneous position on the imaging plane, which is gated by the size of the opening and the resulting weight and durability of the shutter components. But electronic flash exposure is based on the wide open state, not the same as continuous light. Shutter curtains can only traverse the film gate so fast due to accelerative loads and strength, this is what imposes the limit to X sync speeds. Most modern focal plane shutters achieve X sync at speeds up to 1/180 sec or so, some get up to 1/250 or even shorter but they're the exception rather than the rule. (Older shutters, like Leica Barnacks and Nikon Fs, had X sync at 1/30 and 1/60 sec, I remember when the first cameras with the Copal Square vertically traveling shutter came out—whee! 1/125 sec! Dang I'm getting old..) When you pass the X sync limit with a focal plane shutter, the flash exposure is abruptly cut off and only a portion of the frame is exposed with the electronic flash burst.
Modern high speed sync with electronic flash has overcome these limitations, at the expense of instantaneous power output (same as FP bulbs, by the way, which is why FP bulbs were such big things to be bright and useful) but that takes careful matching of flash unit and shutter timing control to coordinate and is limited to dedicated flash units integrated with the shutter's timing circuitry. Other tricks with sensor cut-off control, etc, also reduce the superiority of leaf shutters' ability to sync over a larger shutter time range as well.
G