A while ago, I tested my old Coreflash CF-D300 flashes with the YN622N-TX “SuperSync” (tail sync) mode and you can see the results here. They worked well, however in order to use these on location I have to cart around a Godox LP800X battery and inverter to give me a 240 volt power supply. The 
Safari’s power 
supply and battery is
optimised for the job at hand, and is therefore much smaller – despite giving roughly the same amount of full power flashes.
I tested it out in much the same way. The camera settings for this test are 1/2000th of a second, f/4.0 at ISO 64. 1/2000th of a second gives useful freezing power for any ambient light – say if you’re photographing a model on a beach with waves crashing on the rocks, or with fabric blowing about. It probably won’t freeze it completely, but you will avoid those awful shadows around a moving subject where they blocked the ambient light from, say, the sky, for a part of the exposure. Aperture and ISO: you can of course trade these and shoot ISO 250 at f/8. The Safari is on half power.
Here’s the results with the dialled in delay number. Numerically, its the reverse of what it should be (a larger delay between the light firing and the shutter firing, should result in the rear curtain being lower in the frame, as it travels bottom to top of frame on my Nikon D810). It’s 3.0 -X <some unit>. Alternatively, you can think of smaller numbers meaning the flash fires earlier – and at 1.0 the flash light is present before the rear curtain starts to travel. We get more fall off at the top as the front curtain was only half way up when the flash light began.
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2.0 |
1.5 |
1.4 |
1.2 |
1.0 |
That black bar you can see is the rear or second curtain. In normal operation and first curtain sync, the flash fires when the first curtain reaches the the fully open position (top of frame). Not when the shutter begins to open. The shutter “speed” we set on our cameras is the time between the first curtain and the second curtain passing the same point. So at a shutter speed of 1/2000th of second, its pretty far up the frame when the first curtain reaches the top and the flash is triggered. Tail sync works by delaying the whole shutter operation , so the flash output is already in full swing by the time the first curtain starts it’s journey. With the right amount of delay, the flash is already burning before the second curtain starts it’s journey.
This does mean, of course, that its getting dimmer as the curtains get to the top of the frame. The rate at which this fall-off occurs is a function of the flash duration. Shorter flash durations: steeper fall-off. The Safari II, although a conventional voltage regulated flash, is actually quite fast. This is great for beating back the sun within normal flash sync speeds as it gets all of its light out in a short time. However, for tail sync, this is not so good.
However, as long as you are aware of this, you can work with it. For example, if you are shooting a model on a beach, the flash will only affect things within range. It has no effect on the sky anyway, so put the sky in a part of the frame that doesn’t get any flash. For my Nikon, that simply means shooting with the camera upside down. Now the black bar is at the top. Alternatively, you can aim the flash at the top of the frame, so the fall of from the light pattern, compensates for the fall off of light over time (and the frame).
