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  • Welcome to the new site. Here's a thread about the update where you can post your feedback, ask questions or spot those nasty bugs!

News: Oh this is exciting for strobist enthusiasts...

Asher Kelman

OPF Owner/Editor-in-Chief
The folks over at RadioPopper have created yet another world's first. High speed sync (up to 1/800th) on a Rx system using E-TTL or manual!

Watch the video here!
Jerome,

As far as I can see this works with just Alien Bees and it's big brother. Also one would have to be sure that the flash duration fits into this window. With the highest W/S setting I wonder if you lose some of the light? With less expensive and older units, the flash duration can be surprisingly long at the highest settings.

Asher
 

Doug Kerr

Active member
Hi, Asher,

Jerome,

As far as I can see this works with just Alien Bees and it's big brother. Also one would have to be sure that the flash duration fits into this window.
What window? With high speed sync the flash overall duration has to span the curtain travel time (perhaps 1/300 sec.)

I didn't know that those flash units offered that. I wouldn't think it is something the R/C could arrange for on its own (but maybe by rapid repeated triggering - who knows).

So I'm overall a little mystified.

Best regards,

Doug
 

Asher Kelman

OPF Owner/Editor-in-Chief
Hi Doug,

I see there are different considerations of the shutter time or "window".

Ultra short flash duration: The "window" is the time for the slit of the DSLR cloth or metal shutter to traverse the sensor plane. If the flash is ultra short in duration, only part of the light sensitive surface will have been reached!

The solution to this, for example with a Canon flash, is to use it in the high frequency mode, where multiple short pulses will illuminate the slit throughout it's travel. I can't imagine how one does this with an Alien Bee in slave mode! Does anyone know?

Prolonged flash duration problem: Here the total duration of the shutter being open (or the slit moving) is too short for the flash duration! This is an issue with classic strobe units, for example, with Lumedyne basic units, when all of 1,600 W/S are put into 1 flash tube. The flash duration can then be as much 1/100 second or longer. That means a portion of the light will not be used and one will get the strange result that as one increases the flash power, the images get no brighter!

So one is not using all the light. Ideally, the peak of the light should be broad enough so the light let in by the moving slit is evenly passed over the sensor surface.

The solution for this issue is two-fold. First split the power to more than one flash tube. for each split one halves the flash duration. Next decrease the shutter speed. For older flash units a synch speed of 1/100 or 1/60 even may be best when using fill power to one tube.

Then again, what is the advantage of this system over Pocket Wizards which work with any brand of studio strobes? So I'd love to hear from a RadioPopper user to know what drives this interest?

Asher
 
I'm sure I am in way over my head here because I do not understand much of what has been said so far. I was very interested in the RadioPoppers though when they were first being developed and readied for production. I almost purchased them for my Nikon system but just never pulled that trigger. The big draw towards them for me and a lot of other shooters was the fact that they not only would trigger my remote flashes but they would do so and use the Nikon TTL capabilities automatically while doing it. With Pocket Wizards, I think, you had to make all of the remote flash settings and adjustments manually and then they just triggered the flashes at whatever settings you had made. With the TTL capabilities your camera would send the information through the RadioPoppers signal and make the proper adjustments to the flash as needed. I just assumed that they now had the capability to do the same sort of thing with the Alien Bees. Am I completely off in my thinking and should I have just stayed out of this conversation? If so, and if I missed the point completely, please forgive me. I am just trying to participate.
James Newman
 

Asher Kelman

OPF Owner/Editor-in-Chief
James,

You have hit the nail on the head! It's the ability to control the settings for up to 3 sets of slaves that is significant. But only the Alien Bees and the big brothers to that same brand. however, a lot of folk use A/Bs!

Asher
 

Doug Kerr

Active member
Hi, Asher,

The solution to this, for example with a Canon flash, is to use it in the high frequency mode . . .
That is, the "high speed sync" mode (although that name isn't really all that descriptive either, since it isn't a special kind of sync but rather a special kind of output burst, although that does require a certain sync scheme)

. . . where multiple short pulses will illuminate the slit throughout it's travel. I can't imagine how one does this with an Alien Bee in slave mode! Does anyone know?
Indeed, thus my comment/question.

Best regards,

Doug
 
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