dwdallam wrote:
Are you using full power on your studio strobes to test? You won't be able to push the x sync much above ratings without increasing the power to the strobes each time. The easiest way to test is to set the strobes on full power and incrementally increase shutter speed.
Using the PW Flex system, I got my Alien Bees 1600 all the way to 1/5000th--where I stopped testing. But I had to use full power.
what camera are you using? The 5d II has a very slow/large shutter.
I'm using a 1DS MKIII. If you're using the Flex system, you can continue to adjust the sync speed and tail of the light in the utility. I do remember something about the 5D series. But I sold my Flex system because of inconsistency, gross inconsistency.
So, I gave up on the flex system. I just sold 4 TT5s, an AC3, and the AC9. After blowing three IGBTs on my 580EX IIs and having LPA upgrade all my flashes by replacing the IGBT and adjusting the flash head, plus coating the internal with the RF coating, I was still getting some really screwy exposures, misfires, black frames, sync problems (on my Canon flashes), and weird things like one of the flash groups wouldn't go off if the camera was near my face, but would go off if I fired it from the hip.
I tried so hard for two years to get those things to work and the people at PW were and are great in all respects, but that Flex system with Canon and the 580EX II flash is just a nonstarter. Haven't heard anything bad from the Nikon Flex system.
I am now the proud owner of the Phottix Odin system, and it is beautiful! Just perfect all the way around. I love them. Damn it's so good to be out from under the stress of working around or not even working with the Flex system. You won;t find all of the adjustments you get with the Flex system, but at least they work.
The two physical constraints with the HSS hack with conventional flash are the shutter curtain speed which is constant for all indicated shutter speeds, and the duration of the flash pulse.
With speedlight HHS the flash is triggered just before the first shutter curtain opens to start the exposure, pulsing the flash at about 40,000 Hz. It takes the first curtain about 1/300th sec to cross the sensor regardess of indicated shutter speed. That's what causes the x-sync limit in normal flash mode; waiting for the first curtain to get out of the way. The larger the sensor the longer it takes the curtains to cross it. Higher indicated shutter speeds such as 1/4000 are obtained by the latency between the two curtains. The curtains move across at a rather leasurely pace of 1/300th sec. spaced 1/4000th sec apart forming the moving slit which exposes the sensor for 1/4000th sec.
The HHS hack works by getting the studio light to fire before the shutter opens so when the curtains start to move it is at peak intensity. I first heard of it a few years abo when someone discovered by accident their 580ex flash in HHS mode triggered their ABs optically before the shutter opened allowing great than sync-limit shutter speeds using the tail portion of the flash. The radio triggers likely do it by reacting to the signal on the TTL pins normally used for the pre-flashes.
But with either method of triggering (radio or optical via a HSS flash in the hot shoe) to get even exposure of the frame the flash duration needs to be in the range of the 1/300th sec or so it takes the curtains to cross the frame. The Catch-22 is that the flash works like a continous source with regard to exposure and as indicated shutter speed is reduced (and the slit between curtains narrow) in an attempt to freeze action with shutter vs. flash duraction a lot of flash power is needed.
HSS is similar to the way flash blubs were sync'd on cameras. They needed time to ignite before the shutter opened.
