Paul C. Buff, Inc. Technical Forum

First, lest I be flamed too much, let me say that I haven't fully thought this through yet. . . Now, with that bit out of the way, with the power sufficiently reduced, is there any practical limitation on how fast the E640 will fire in a burst up until the caps are too far drained? In other words, how much additional delay is reasonably needed between pops? What I am curious about is if I were to fool my camera into thinking it's in FP/HSS mode so it trips the flash early, could I actually (without firmware changes to the E640 itself) drive it at a fairly high frequency (via the 1/8" sync port) for a very short duration say 1/500 or less of a second?

I know Paul isn't an FP/HSS sync "hack" fan and also that this isn't necessarily going to produce stellar results, okay it may really stink as at 1/10000 of a second duration (it gets a bit better, but just for sake of simplicity) without any extra delay between pops you would only be able to fit in 10 pops in 1/1000 of a second, so coverage may not be so even. I'd just give this a try, but I don't have a flash capable of FP mode that I can use to trick my camera into triggering early and would need to borrow one to test this out. . .

If nothing else, it could make for some cool stroboscopic effects. . .

Of course I'd be like a kid in a candy shop if I had some "advanced" menus that let me play with this kind of stuff by tweaking rates and delays and such to a point where I'm really up there in frequency (5-10KHz). . . I know, I know, lots to do still and I'm by no means complaining, I *love* the fact that I can even think about how this stuff may be possible with these lights rather than being stuck with stuff from the stone age;->

-Daniel

So I said I didn't think about this much before firing off my mouth (or keyboard as the case is). . . I just realized that what I'm asking for may not really be about the number of pops I can get as fast as possible, but instead about achieving the absolute minimum delay between pops. Here is my thinking. If you can keep the tube lit constantly as long as the shutter is open similar to what folks were doing with the "old style" bees on a single pop, but with multiple pops on the Einstein since they're so darn quick, then you could at least get even coverage. So the questions may actually be this:

1 - If the Einstein is fired and the tube is still lit and you provide the signal to fire again, will it fire again immediately after the first flash is complete, or will it just drop (debounce) the signal?

2 - What is the minimum delay between firing?

3 - I know I could measure these things, but I'm short some photo sensors and it's 10pm nearly, so I'd have to go buy parts and drag out a scope and then pretend I know something about hardware when I'm really more of a software guy;->

-Daniel

Tough question to answer, really. I am not part of the engineering team, so I cannot give you a full explaination. But, there may be an absolute minimum distance between pops and still get it to fire every time, yet the E640 could be set to a longer time due other factors that arise from a short timing. In fact, we did regulate that in v.22 firmware as it was double tripping in rare instances via sync cord.

In its current configuration, I doubt you could hack it to HSS pulsing.

Einstein can fire at 12 fps . . . every 1/12 second. The flash lasts a maximum of 1/50 seconds, so there is no way it can be fired will it's still burning . . . that would take 600fps.

Thanks Paul, that pretty much nails the question! I realized that you would probably be debouncing or otherwise rate limiting the input, so firing as quickly in succession as I was thinking would probably be out of the question, though I was hoping that with longer durations the debounce period may be short enough that it could be coaxed into firing with little to no delay after the tube was done burning, though your math is pretty simple and generally 12fps is pretty darn fast! Is this handled the same if used with a CSXCV module as opposed to the 1/8" sync port?

It's 12fps with either sync jack or CSXCV. The tube cannot fire immediately after extinguishing because the capacitors have to recharge and the sync circuit itself must recharge.

It's possible to "simmer" the flash tube to ultimately do HHS, but this is a lot of programming and rework and involves different routines for different camera protocols.

Simmering a flashtube involves pulsing it off and on at a controlled rate the keeps it burning at a lower intensity to extend the flash duration . . . a necessary procedure for true HHS. It's a very complex thing to keep the waveform a "flattop" and to keep the color temperature stable.

Don't hold your breath for this though.

Thanks, I figured the answer was the same, but thought I'd ask anyhow. What I didn't know was if you actually had to top off the caps fully between shots, or if a shot could be made before the charge cycle had finished. It's all very interesting to someone like me (a geek at heart), though the answer of the same 12fps max for both triggering mechanisms is more than sufficient. :)

I'm not holding my breath on the true HSS front, I know you've repeatedly told people not to and that you don't care for it so much anyhow, which is why I asked the questions I did hoping a hack-around may be possible. . . Just to poke the bear a bit though, it would be such an awesome feature to have! There are times while mixing ambient and strobe with sports that HSS is actually the only (current) option to freeze motion. Some day we may get different sensor or shutter designs again, but for now with current generation SLR equipment you're pretty limited.

Don't get me wrong, I absolutely adore my Einsteins as-is, I just know there is still a lot of potential upside that may come down to programming and not hardware changes. That's exciting since it should help make an already extremely marketable product even more so over time with a lot less investment than the usual hardware redesign!

-Daniel

You can fire Einstein before it's recycled. But if you fired several FPS at full power, the first pop would be big and the rest at low power because the caps would not have to to recharge.

But if you reduced the power to say 1/4 power you could fire off several shots at say 3-5fps you would only see a much smaller progressive lowering of exposure following the first shot. This is because the first shot would leave 3/4 of the charge on the caps, so the second shot would only suffer about a 3/10f lower exposure.

That is what I originally thought and follows my experience as far as being able to pop before fully charged when shooting action sequences with the power set a bit too high, but I misunderstood your previous comment, sorry for my confusion and thanks for being there to straighten me out!

-Daniel

Just thinking out loud here, as HSS is not something I really need, but I've been playing with multipop... suppose one had a pair of E640's (or more) and fired them at 12fps, but staggered them... effectively giving 24fps. I know my MultiMax can fire an E640 in multipop mode with an interval of .08 sec (not sure how steady the power is). Add an identical unit with a .04 sec initial delay... might work with some experimentation.