AF 360FGZ Flash speed sync question

I've searched this forum but I've found no clear answer on these two questions:
1) the AF360FGZ flash specs say that it has high speed sync. Does this mean that on it will synchronize with shutter speeds above 1/100 (up to 1/2000 or 1/4000) on K10 or MZ-5n?

2) if this flash is able such high speed synchronization, why the built-in flash synchronizes only up to 1/125?
Thanks, Jiri

High speed flash sync requires that both the body and the flashgun are able to support it. The K10D can, the MZ-5n can't. With the K10D and AF360-FGZ you can indeed sync at higher speeds.

High speed sync works by taking multiple flashes at different points in the shutter cycle. Normal flash requires the shutter to be fully open when the flash fires (once), and the shutter is only fully open at speeds of 1/125 and below.

G

The more I think about HSS, the more it boggles my mind.

The K10D has a flash sync speed of 1/180, and with HSS it can sync all the way up to 1/4000, AIUI. At a shutter speed of 1/4000, presumably the gap between the curtains is only about 1/20 of the frame as it crosses the sensor.

So does that really mean that the flash must flash about 20 times during the exposure? Presumably the exposure itself must last about 1/180s in total, but even so.

And how accurate must the timing of the flashes be, so as not to miss bits, or expose parts more than once?

Have I missed something, or is it really that precise? I can feel some tests coming on...

If the shutter speed is 1/4000 than the exposure simply can't last 1/180s or am I wrong? But anyway it seems to be correct that the flash should 'flash' at least 20x so that the whole frame is properly exposed. Any other ideas, links?

I was assuming that the curtains themselves travel across the frame at about the same speed irrespective of exposure, once it's shorter than the sync speed.

So they'll travel at the same speed, thus taking the same total time to get across, at 1/4000 as they do at 1/180.

Of course, at 1/4000s they'll be much closer together, as I said, so each part of the frame will only get the 1/4000.

If my estimate of 20 flashes is right, then it's 20 flashes in 1/180s or thereabouts, not 20 flashes in 1/4000s, but the precise timing still amazes me.

And it works with two flashguns, and wirelessly, as I understand it.

You are mixing things up.

You can either take a conventional flash exposure, with any old flashgun, and the flash will fire while the shutter is fully open.

The length of time a shutter is fully open varies from camera to camera, but with a focal plane shutter is usually no more than 1/250, and generally rather less. This is the "flash sync speed".

With HSS, the flash sync speed doesn't apply. The gun fires a number of flashes as the slit formed by the shutter moves across the sensor/film. Provided they can sync it right, and the flashgun is powerful enough, there is not really any limit to the HSS speed. On the K10D sync'ing can be at the camera's maximum shutter speed.

G

It seems like that I missed some photographic education. I'll have to think about all this but even now it seems to be much clearer for me. Thanks for explanation.

I think you meant this, George:

The length of time a shutter is fully open varies from camera to camera, but with a focal plane shutter is usually no less than 1/250, and generally rather more. This is the "flash sync speed".

I knew what he meant. 1/60 must be less than 1/125 because 60 is a smaller number.

Kim

I knew what he meant too. But it had to be done...

One day I hope to use a word he doesn't know, too.

Fair cop!

G