flash not synced with camera shutter

I just recently purchased a pair of V6s. I shoot with a Pentax K5 and am using a single Pentax AF-540FGZ flash. I can get my flash to fire just fine, but it seems that it is just a slight bit out of sync with the camera. My images consistently come out with the upper portion slightly shadowed, no matter how I aim the flash. I have tried various shutter speeds ranging from 1/30 second to 1/125 second with no change to this shadow. I have made sure the delay is turned off on both V6s. The units are communicating (I can control power on the rx from the tx, and the flash fires when I push the test button on either the camera unit or the flash unit.) Also, without changing any settings on the flash, if I remove the V6s and connect the flash to the camera with a standard sync cord, the flash produces the proper image with no shadowing. I am new to radio triggers in general, but have pored over the Cactus user manual, and have watched (& followed) and online video showing how to set up the V6s. Any help would be appreciated. Thanks!


  • It is strange that you are seeing a shadow at the top of the image.

    A delay caused by the triggers would manifest itself by a shadow (black bar) at the bottom of the image.

    Are you seeing a slightly darker area, or a black bar?

    Unless in your experiments you are somehow moving the flash in a way that could cause a shadow or uneven illumination, the only explanation for a black bar at the top of the image is that the flash is firing too early (before the first curtain has completely opened). That would be rather unexpected.

    Nevertheless, you could try to set a delay of 1ms or 2ms with the V6 to see whether this affects the shadow you are seeing. If the flash is indeed firing too early then a delay should address that.

    I'm using my V6 with a Pentax K-5 II and a number of flashes (including a Metz 58 AF-2) without any problems. I just tried to use the Metz with the 540FGZ profile and it works without causing a shadow (or black bar).
  • It shouldn't make a difference, but try swapping the V6 units, i.e., use the current receiver as the transmitter, and vice versa.

    Also, try to update the V6 to the latest firmware, if you can. See the "Downloads" tab on the V6 product page.

    The latest firmware is 1.1.007 and you can check your current firmware version by keeping group buttons "A" & "D" pressed while turning the V6 on (make sure you don't press any other buttons).

    It shouldn't be necessary to update the firmware, but I'd still try it just in case.
  • Thanks for the suggestions! I found that a delay of 5ms did the trick. Exposure is great from shutter speed of 180th second or slower, with no shadowing at the top. I had already done the firmware update in one of my earlier attempts to correct the problem, but it didn't help. Not sure just why I had to do the delay, but I'm glad I have this working!

  • Great to hear that you could address the problem and I'm glad I could help.

    I wonder whether your camera may have a slight issue with the correct X-sync timing. If that were the case, however, you should see the same shadowing with the AF540 FGZ connected to the camera directly. If you wanted to investigate this, you should set the AF540 FGZ into manual mode in order to rule out any P-TTL influence.

    Just seems wrong  that the V6 would be able to speed up the triggering of the flash, but the main thing is that you have a working solution that you are apparently happy with.

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