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| p.2 #3 · p.2 #3 · Options for Hypersync with canon 5D II & Elinchrom or Einstein |
How would short flash duration work with faster-than-sync shutters? Wouldn't a long duration be required to keep some light going during the travel of the shutter slit across the sensor?
With a speedlight which is what I've done this with the 'Peak' can be centred around the middle of the frame. It does result in maintaining the maximum output even at higher shutter speeds up to a point - and there are gradients to the top and bottom. (The duration is not long enough as you point out). The flash pulse which is relatively short is not enough to provide an even illumination across the frame, it can however (because the timing can be set to suit the shutter), be centred in the frame.
Its a compromise.
But Speedlites do it by pulsing the tube to get a long duration, right?
Thats what they do yes. But in the situation described using the ControlTL setup and retiming the sync I could get +1.6 stops flash advantage with an acceptable compromise using a Speedlight by setting 'HSS OFF' (NO pulsing) just using full output. Full output is supposedly 1/1000s for the SB800 I used, the Quadra is supposedly 1/1200s at full output with an 'S' head. The difference in result should be negligible.
Without any retiming and using full output of a Speedlight (SB800/SB900) with no pulsing, I can sync at every shutter speed up to 1/8000s using only the inbuilt FP mode timing in the camera. This is the 'hack' it uses the 'Tail', or the 'Peak' and the 'Tail' depending on your setup. Some equipment works better than others for this and you just can't 'fix' the equipment which is unsuitable unfortunately.