Intermittent flash sync fail

Discussion in 'Beginner Questions' started by jdbanks, Apr 14, 2019.

  1. I'm shooting a Nikon D5600, 1/200 shutter speed, 100 ISO, f5.6. Using Pocket Wizard triggers on camera and one studio light, with the second light on slave mode. Doing portraits at church for a new directory.

    Last week I had no problem. Today, intermittently, I would get a dark streak along one side, which suggests to me a sync fail. But my settings aren't changing between shots, and I'm stumped.

    The triggers have good batteries, the Nikon has a freshly-charged battery, the lights are plugged into a power strip. I'm tethered into LR Classic on my laptop.

    I've used a similar setup multiple times in the past with no issues.

    Any help would be greatly appreciated!
  2. Hi, no direct experience with that camera, but I've spent more than a bit of time dealing with Studio shooting problems, so...

    First thing I would do, during the shooting session: try reseating the hot shoe piece, as well as the receiver. (I looked up your camera, so I know it doesn't have a sync connector, else I might suggest to try that into the PW unit also.) If you have time, inspect the contact surfaces of the hot shoe and PW transmitter, even wipe them down with a clean cloth.

    If it happens again during shooting I'd go to a slightly longer shutter speed. I know that your camera sync speed is 1/200, but if anything happens to slightly delay the flash firing, this could get you into shutter sync problems; the slightly longer shutter duration should help get you past this. If the problem still keeps up, I'd consider removing the PW setup, using your pop-up flash to fire the studio lights via their optical slaves (manually set the pop-up flash to a low power setting so that it doesn't affect the lighting too much). Also be aware that the camera may switch over to the pop-up flash white balance unless you have specifically set a manual white balance.

    When you get a little breathing room, I'd swap out the PW batteries with something "known good," maybe even bought new from a different source.

    After the shooting is done, and you have time on your hands, I'd do some troubleshooting. I would not feel comfortable going back to important work again until I had a good idea of what went wrong.

    First thing I'd do there is to check the exif data in each image to confirm that they are all actually shot at the shutter speed you think is set. Next I'd confirm that the dark band is actually occurring in the place you would expect as a result of a "too short" shutter speed (you can induce this with a progressively shorter shutter duration).

    If no problem is found yet, I'd try testing the consistency of the flash delay, using PW system. You should be able to do this by setting a shutter speed that is too short, specifically causing a dark edge (note, the camera might not allow this with pop-up flash, but I'm guessing that it will with PW). Then shoot about 10 or 20 shots to see if the dark edge position stays consistent or if it floats around a little. If it floats around, this means that the flash trigger is not consistent, or perhaps a shutter issue. To troubleshoot "floating," switch your sync from the PW to optical triggering via your pop-up flash; if this suddenly becomes consistent then you know that the variability is coming from the PW system (keep in mind that the camera might not allow faster shutter speeds with pop-up flash enabled, but it likely would with a no name hot shoe flash, et .) Note that optical triggering is normally VERY fast, and consistent. Whereas the radio trigger, while fast, normally is slower (they typically send a longish coded signal to prevent accidental triggering from someone else's system). And because of the possibility of a random signal disrupting the coded signal, it's good practice to send it several times (these are all much faster than a human can see, but MIGHT give a visible effect related to shutter sync).

    Anyway, these are the places where I would start. A couple more random notes - check the camera menus to make sure you are on "normal" sync mode (meaning NOT on second-curtain sync, or whatever Nikon calls it), and if anything looks funny about the triggering event try swapping the PW receiver to the second studio light.

    Best of luck with it.
    Last edited: Apr 14, 2019
    jdbanks likes this.
  3. By a dark edge, I take it you mean the bottom long edge of the frame?

    You've just been lucky so far using your camera's maximum X synch speed with radio triggers.

    All radio triggers, no matter how expensive, introduce a slight encoding/decoding delay. It's only a few hundred microseconds, but enough to prevent clean synching with electronic flash.

    You must drop the shutter speed to the next lowest - in this case 1/160th second. This is pretty common knowledge to anyone who regularly uses radio triggers.

    PS. Some 'channels' introduce more delay than others. It might be worth experimenting to see if there's a Tx/Rx channel that consistently gives a clean edge, but it's certainly safer just to drop the shutter speed a notch.
    Last edited: Apr 15, 2019
    William Michael and jdbanks like this.
  4. I agree with Rodeo_Joe; doing as he suggests worked for my similar problem with a Chinese No-Name radio trigger and a few optical slaves to follow.
    jdbanks likes this.

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