Open Photography Forums  
HOME FORUMS NEWS FAQ SEARCH

Go Back   Open Photography Forums > OPF Welcome Hall > Breaking News

Breaking News Updates, innovations, equipment: moderated!

Reply
 
Thread Tools Display Modes
  #1  
Old February 18th, 2009, 07:07 PM
Jerome Love Jerome Love is offline
Member
 
Join Date: Jul 2007
Location: Sacramento, CA
Posts: 76
Default Oh this is exciting for strobist enthusiasts...

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!
Reply With Quote
  #2  
Old February 23rd, 2009, 12:25 PM
Asher Kelman Asher Kelman is online now
OPF Owner/Editor-in-Chief
 
Join Date: Apr 2006
Posts: 32,735
Default

Quote:
Originally Posted by Jerome Love View Post
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
__________________
Follow us on Twitter at @opfweb

Our purpose is getting to an impressive photograph. So we encourage browsing and then feedback. Consider a link to your galleries annotated, C&C welcomed. Images posted within OPF are assumed to be for Comment & Critique, unless otherwise designated.
Reply With Quote
  #3  
Old February 23rd, 2009, 05:35 PM
Doug Kerr Doug Kerr is online now
Senior Member
 
Join Date: May 2006
Location: Alamogordo, New Mexico, USA
Posts: 8,194
Default

Hi, Asher,

Quote:
Originally Posted by Asher Kelman View Post
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
Reply With Quote
  #4  
Old February 23rd, 2009, 07:11 PM
Asher Kelman Asher Kelman is online now
OPF Owner/Editor-in-Chief
 
Join Date: Apr 2006
Posts: 32,735
Default

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
__________________
Follow us on Twitter at @opfweb

Our purpose is getting to an impressive photograph. So we encourage browsing and then feedback. Consider a link to your galleries annotated, C&C welcomed. Images posted within OPF are assumed to be for Comment & Critique, unless otherwise designated.
Reply With Quote
  #5  
Old February 23rd, 2009, 07:50 PM
James Newman James Newman is offline
Senior Member
 
Join Date: Apr 2007
Location: Somewhere in the Midwest
Posts: 658
Default

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
__________________
James Newman
Chicagoland
www.pbase.com/jnewmanco1 c&c welcomed
Reply With Quote
  #6  
Old February 23rd, 2009, 08:24 PM
Asher Kelman Asher Kelman is online now
OPF Owner/Editor-in-Chief
 
Join Date: Apr 2006
Posts: 32,735
Default

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
__________________
Follow us on Twitter at @opfweb

Our purpose is getting to an impressive photograph. So we encourage browsing and then feedback. Consider a link to your galleries annotated, C&C welcomed. Images posted within OPF are assumed to be for Comment & Critique, unless otherwise designated.
Reply With Quote
  #7  
Old February 24th, 2009, 02:45 AM
Doug Kerr Doug Kerr is online now
Senior Member
 
Join Date: May 2006
Location: Alamogordo, New Mexico, USA
Posts: 8,194
Default

Hi, Asher,

Quote:
Originally Posted by Asher Kelman View Post
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)

Quote:
. . . 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
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 02:27 PM.


Posting images or text grants license to OPF, yet of such remain with its creator. Still, all assembled discussion 2006-2017 Asher Kelman (all rights reserved) Posts with new theme or unusual image might be moved/copied to a new thread!