Fuji x100s Flash Sync Tests

The previous post looked at how the Fuji x100s shutter syncs with an external flash. The bottom line was that the shutter takes about 1/600 of a second to close. So any shutter speeds faster than that can’t have a fully open aperture, because the shutter is already partially closed when the exposure starts. This means some light can be lost while using a flash at high shutter speeds.

Here’s an example. Suppose you set the Fuji to a wide open aperture of f/2, and its max shutter speed of 1/4000 of a second. You have a flash connected, set to manual, at some power level. If the t.1 time of the flash is longer than 1/4000 of a second, you’re gonna lose light. A Canon 430EXII flash has a t.1 time of 1/4000 of a second when its set to 1/8 power. So as long as you’re set to 1/8 power of less, you shouldn’t lose too much light.

I decided to test this idea. At the same time, I was curious how well the Fuji would sync with the flash if I used my Pocket Wizard remotes, instead of a hard-wired connection between the camera and flash.

To test this, I put the Fuji on a tripod and pointed it at a couple of white doors. Boring, but it worked. The 430EXII flash was also on a stand, with no modifiers, other than the 1/4 cut of CTO gel I always have on this flash. The camera was set to 100 ISO. The room was dark enough that ambient light was insignificant.

The image below shows some results. The left most column of images were taken with the Pocket Wizards (Flex TT5 and Mini TT1). The flash was set to manual, 1/64 power. Going down in the column of images corresponds to increases in the shutter speed, from 1/125 up to 1/4000. By the way, the only way I could get the Pocket Wizards to work at all was to set them to basic trigger mode, which eliminates any possibility of adjusting the triggering time delays. It just a dumb, basic trigger. You can see that the camera was able to sync with the flash at shutter speeds of 1/500 and slower. Above that value, not so much.

4-case comparison small

On the other hand, when the flash was connected to the camera with a cord (next column to the right), with no Pocket Wizards, the camera and flash synced nicely all the way up to 1/4000. There is some loss of light at the highest shutter speeds, but not bad.

At a power setting of 1/8 on the flash (rightmost two columns of images), I got basically the same result. The Pocket Wizards worked fine up to about 1/500. The cord synced all the way up to 1/4000, with again some loss of light at the highest speeds. But still, this is pretty cool. I can see why people are so excited about this camera.
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