Using a Canon 580EX with pocket wizards over x-sync speed?

Discussion in 'Canon EOS' started by wakeforce, Mar 8, 2006.

  1. First, is it possible? If so, how? I have an x-sync of 1/250 and it is
    not enough for shooting outdoor sports during the day.

    I tried using high-speed sync but I think it only works in manual. So
    is there a way to shoot at 1/1000 with a canon 580EX and a set of
    pocket wizard plus ?
     
  2. The simple answer is no.

    The following is something I wrote in another forum, but explains the problem that you would run into. It has to do with the nature of a focal plane shutter.

    ********

    Focal plane shutters (common on SLR cameras) consist of two "curtains", usually made of rubberized cloth (in old film cameras) or very thin metal. The first curtain (which I will call the "leading" curtain) normally covers the film or sensor, hiding it from the light coming through the lens. When you take a photo, the leading curtain moves across the film/sensor to expose it to the light. After the leading curtain has moved, another curtain (which I will call the "trailing" curtain) starts to move, again covering the film/sensor to hide the light from it.

    At shutter speeds below the "Max Sync Speed", the leading curtain travels all the way across the film/sensor, fully opening the film/sensor to the light, before the trailing curtain starts to move. At higher shutter speeds, the trailing curtain starts to move before the leading curtain has completely travelled across the film/sensor. What happens to create the very fast "shutter speeds" is that an open slot between the two curtains travels across the film/sensor.

    While old focal plane shutters (like in my Nikon F cameras from the 1960's) travelled horizontally, the shutters in most modern SLR's travel across the short distance of the film/sensor frame. The concept of "curtains" turns into one of "blades", but the travel concept is still the same. The leading blade moves first, uncovering the film/sensor, and the trailing blade follows, covering up the film/sensor.

    The advantage of the blade style of focal plane shutter is that it can move across the whole film/sensor area faster than the old style curtains. Thus, the maximum sync speed is higher than in the old cameras (max 1/60 for my old Nikon F's, and 1/250 for the 20D).

    The concept of a maximum sync speed, however, still applies. If you try to use a flash at higher shutter speeds (faster than the shutter speed at which the leading curtain/blade is fully open before the trailing curtain/blade starts to move), part of the film/sensor will be covered by one or the other of the curtains/blades when the flash (with a very short duration) goes off. Part of the film/sensor will not "see" the light from the flash, and that part of the image will be either black or very dark.

    ********

    Speedlites (like the 580EX) can work in a "high speed sync" mode, but to do so they emit a long burst of flash light while the "slit" of the focal plane shutter is going past the film/sensor. The Speedlite can only do this when it is fully connected to the camera, however. Thus, your hope of using high speed sync with a 580EX remotely triggered via a Pocket Wizard setup will not work.
     
  3. Thanks for explaining focal plane shutters, I knew they were the problem but I was wondering if there was a way of making the 580EX work in high-speed sync even tough it is not fully connected to the camera. Looks like it isn't, I'll have to think of other ways to do what I want!
     
  4. I've invested in PW MultiMAX's and would really like to understand what was said in this thread. What do you mean by "x-sync" speed? What off-camera cabling are you using for your 580's? My understanding is that the only option for this is the Paramount PW-MHSF1. Is that what you are using?

    It's not possible to shoot at 1/1000th of a second with 580EX off camera controlled with PW's?

    I understood the concept of a dual curtain exposure in digital SLR's, but the explanation seemed to pivot around one statement: "Speedlites (like the 580EX) can work in a "high speed sync" mode, but to do so they emit a long burst of flash light while the "slit" of the focal plane shutter is going past the film/sensor. The Speedlite can only do this when it is fully connected to the camera, however."

    Um, without appearing stupid, why? There must be compatibility issues. If the 580EX can do it on camera, why not off? Can the 580EX function in high sync mode with the ST-E2? Are there manual settings on the PW's being overlooked?

    Are there other flash systems that can operate with digital SLR's in high sync mode with PW's? I like the 580's but if there are other choices for high speed sync with PW's, please post.

    Thanks.
     
  5. Michael, there are things the Speedlites can do when fully connected to Canon EOS cameras. In order to accomplish the magic (which includes the ability to calculate flash exposure based on analysing a pre-flash), the camera and Speedlite need to communicate with each other. That's why there are several smaller pins in the hotshoe.

    Shorting the large center pin in the Speedlite's hotshoe (to the connections at the edge of the hotshoe) will trigger the flash, but if the others don't make connection and enable the camera's communication, none of the extra magic can happen.
     
  6. Understood.

    Are there other flash systems besides the 580EX that can offer high speed sync off camera?
     
  7. I'd love to know if there is something available too, it would open up a huge range of possibilities.
     
  8. Try using the Canon infrared wireless system (either with a 5##EX series or a STE2). I just tryied it last week (with a 580EX as the master and a 420EX as the slave), and it worked fine (at 1/1000s).


    Ruben
     

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