The three main factors that affect HyperSync are shown and tested independently:
- Shutter speed
- HyperSync Offset
- Flash Duration / Flash Power
The very obvious effect of going over your x-sync speed. I'm currently using a Canon 1DS Mark II and have an x-sync speed of 1/250.
The images are very boring horizontally, so I combined photos with varying shutter speeds. The numbers across the top are my shutter speed.
Canon 1DS II @ ISO 100, f 2.8
580EX II @ 1/128 power
The black band at the bottom of the screen is caused by the second curtain closing before the flash fires.
HyperSync Offset
RobGalbraith's HyperSync writeup (pg. 2 on) will do a much better explanation that I will.
HyperSync Offset can be adjusted from 0 to -2500. The more negative the number, the sooner the flash will fire. Unfortunately I didn't test -2000, -2250 and -2500, but you should know what to expect.
Canon 1DS II, ISO 100, f 2.8
580EX II @ 1/128 power
Click the photo to see the animated gif.
I'm a little unsure why the HyperSync offset of 0 is producing a slightly darker image. I will have to investigate this later.
Flash Power / Flash Duration
The graph below shows the intensity vs time for a full power flash.
Most speedlights squelch a full power flash for dramatically improved flash durations.
Canon 1Ds II @ ISO 100, 1/1000
580EX II
The full power flash duration is much longer than exposure duration. To make the most of this, I've found out that I can shoot 1/640th at 1/1. I hope to follow this a little bit more in depth by comparing High Speed Sync (HSS) with 1/1 shots in a later post.
It's also interesting to note that 1/8 to 1/128 are roughly the same duration.
2 comments:
Hi Gary,
I have read that you are getting 1/640 sec with your hypersync on 1Ds Mark II + 580 EX II. How were you able to get this? As I am only able to get a clean frame at 1/320 sec using 580EX.
Thanks, John
It is probably best to think of this problem from the point of view of your flash:
1. Use a long flash duration. The last photo shows the flash duration as a function of power.
2. Determine what part of the flash is useable. In the graph of intensity vs time, the flash power rises sharply and drops off slowly. In the last photo (flash duration vs power), you can see the flash firing at the bottom and slowly fading away towards the top of the Y-axis for various power levels.
3. Adjust HyperSync to control when the flash starts (the bottom of the photo) and shutter speed to cut off the tail end of the flash (the top part of the image). You can see the effects of shutter speed and HyperSync in the first two photos.
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