Nikon Speedlight SB-700 won't fire brighter than about 1/2 power


I'm experiencing a problem with the Cactus V6 and Nikon Speedlight SB-700 combo in Rx mode.

With the V6 Tx unit set to 1/1 power, and the V6 Rx unit under the SB-700 showing 1/1, triggering the flash from the Tx unit's test button produces a bit less than a 1/2 power burst. It does this consistently. I can adjust the power up and down without a problem from the Tx unit, but there's little or no difference between just under 1/2 power and 1/1 power in the brightness of the light or the (too-short) recycle time. If I press the test button on the Tx unit, however, the remote SB-700 will fire slightly brighter, still not 1/1 but closer. 

Then, if I put the Tx unit (no flash attached) onto a camera, and press the shutter button on the camera, the flash will fire near to 1/1 power. If I press the Tx unit's text button after it has been mounted on and fired on the camera, then the remote SB-700 fires at near full power.

I can tell all this from the brightness of the light and the length of the recycle time. It's pretty easy to discern.

The problems are the same with firmware v1.052 and v1.060 loaded in my set of V6 units. The SB-700 profile has been correctly selected.

In brief testing with a Canon Speedlite 600EX-RT in place of a SB-700, things work fine: the remote flash fires at full power when the Tx unit is set to 1/1. The problems appear to be relegated to the SB-700. (Plus I see mention of a similar problem affecting another user and his Speedlight SB-910 in this thread.)

Please advise if I'm doing something wrong, if there's a workaround or if a fix can be made in a future firmware update.


-Rob Galbraith


  • edited July 2014
    Thank you so much for your report.

    Based on your description, our engineering team has addressed to problem about the brightness at 1/1 by V6 on Nikon SB-700 or SB-910. We will have the firmware update within this week to fix this problem.

    On the other hand, either pressing the test button on the Tx's unit or pressing shutter button the camera, both Tx's transmit the same signal to Rx. Hence the flash output is supposed to be the same. Unfortunately, we are unable to replicate the problem you mentioned previously. Can you provide more instruction?

    Look forwarding to hearing you soon.

  • Hi,

    I'm glad to hear that a firmware fix will soon be available.

    Regarding the apparent difference in output depending on how the remote flash is triggered: I'm traveling this week and don't have the V6 etc. with me, but I will post more info once I'm back home and can do additional testing.

    -Rob Galbraith
  • Hi. We have uploaded a new firmware that fix the incorrect light output on Nikon SB-700, 900 and 910. You can download and update your V6's through the Cactus Firmware Updater. The latest version is V1.0.173.

    This update doesn't just fix the said problem. We also added two new features: Selection Dial Lock and Group Sequence. Please have a look at V6 Firmware Updater Notes for more information,

  • HI,

    Thanks for tackling this problem, I look forward to testing it out in a few days.

    -Rob Galbraith
  • I'm glad to hear that. Just let us know when you have any concern.

  • edited August 2014

    I've given firmware v1.0.175 a try. The power setting problem with the SB-700 is worse than before, and not consistent. While I can see the Rx unit is receiving the power-change commands properly, the remote flash is sometimes firing at full power when set to 1/2, it's sometimes firing at less than half power when set to 1l1, it's sometimes firing at full power when set to 1/4 power and so on. There's no consistency to the brightness of the flash's output and the power level setting. It's a mess.

    This is all based on triggering the Rx unit from the Tx unit's test button only, I haven't tried anything else so far. Neither a camera nor a flash is attached to the Tx unit. I've tried swapping in new batteries, changing channels and changing the working range from long to short. None of these things help.

    If I put a 600EX-RT on the receiver instead (changing the profile to this flash model too of course) then the power increments as expected. At 1/1 it emits full power, and with each 1/3-step adjustment down from there it puts out progressively less light. 

    So the Tx and Rx units I'm testing can work properly, it seems. Just not with the SB-700.

    -Rob Galbraith
  • Hello Rob,

    Thank you so much for your feedback to the latest firmware. Our Engineering Team is trying to replicate the problem you previously mentioned. On our SB-700, the power level constantly changes from 1/128 to 1/8 wirelessly controlled by V6. But when the V6 set to 1/4 to 1/1. The power output is incorrect occasionally. For example, the power level has about +/-1 Ev difference at 1/2 and 1/1. It doesn't always happen, but it does sometimes. We are checking its pattern and need some time to address this problem.

    One of the possible reason may be the adjustment on the SB-600 EV compensation at TTL mode. It will change the flash output value on the V6 / flash. Please be sure to set the EV +/- to 0 while using with V6. Hope it will be helpful.

    Other suggestions and information of your setting is appreciated. We will investigate any possible solutions.

    Thank you and look forward to hearing you soon!
  • Hi,

    Your description closely matches my experience, exact that the problem is nearly constant for me at the upper power settings and, even on 1/4 power, the flash is doing a full power dump at times.

    So, it's constantly inconsistent, to the point where the upper power levels aren't usable at the moment.

    At lower power settings, probably at 1/8 and lower as you say, output consistency doesn't appear to be a problem.

    Flash exposure compensation was/is set to zero on my SB-700. The flash was turned on first, to TTL mode, before turning on the V6 to Rx. I've been unlocking the flash and changing the zoom head to 16mm as part of the setup routine. The illumination pattern is set to Standard (the three-position switch's top position). I've been going back and forth between 1/3EV and 1EV adjustment increments, and controlling all groups or just one group.

    Thanks for continuing to try and solve this weirdness.

    -Rob Galbraith
  • Hello Rob Galbraith,

    We have emulated numbers of scenario that may replicate the problem you mentioned about inconsistent power adjustment.

    We found that whenever a Rx unit uses UNLOCK function with SB-700. It will be inconsistency after making changes on the flash setting. Approximately, the first 3 shots triggered by the RX unit right after the unlock status, the flash output may become inconsistent.

    My wild guess is that the Rx unit switches from Unlock and Lock status frequently that may confuse the communication to the SB-700 . For example, to set the TTL mode to manual mode on SB-700, adjust zoom range, etc. The SB-700 may store the previous setting and not yet transfer to the RX. After few shots or short period of time, the communication resumes between the SB-700 and the Rx unit. The power output by the Rx unit then goes back to normal. So, whenever the Rx unit adjusts the power from 1/1 to 1/4 in descending order, the output seems to be inconsistent. But after 1/4, since the Sb-700 with Rx unit has been fired few times, the output then back to normal.
    Not sure that happened to you but it would be a great help if we can narrow down the problem area and focus on the most possible reasons. Your comment is highly appreciated.

    Thank you and look forward to hearing you soon.

  • Hi,

    Your description doesn't quite match my experience. Even if I don't use the unlock function, and regardless of whether I go from full power down to 1/4 power or just randomly select power settings between 1/4 and full, the flash fires at a power level that's clearly different than what I've set. And, with the power set at or near full power, the flash output is always less than what has been set. This is true through dozens and dozens of flash pops. 

    I wish I could give more info that would help narrow down the problem. All I can tell you right now is that whatever I seem to be doing, the higher power settings just don't work right.

    If I discover something about what's triggering the problem I'll post again.

    -Rob Galbraith
  • edited August 2014
    Hello Rob

    Thank you for your information. We have 2 new findings that may address the problem.

    1. Full power (1/1) in M mode vs maximum power in TTL mode

    The SB-700 at TTL mode doesn't produce the same power output at the full power as it sets at Manual mode. We put the grey / black card in front of the camera lens, set the flash at TTL and take a shoot. The grey card was placed at a position to confuse the camera TTL system so that it would instruct the SB-700 on above to give its full power in TTL mode.

    Using a light meter to measure the amount of light output, you would find that the maximum power you could achieve in TTL mode would be slightly weaker than you could have when the flash is set to M mode at its full power (1/1). The difference is around 0.1-0.2EV. The reason is that the SB-700 has a pre-flash right before the main flash in TTL mode for light metering. The difference in output between the M mode and the TTL mode reflects the energy reserved or consumed by the pre-flash.

    From your experience with the V6, when you say it cannot fire the SB-700 to its maximum power, did you mean the small (around 0.2EV) difference that is related to the energy reserved for the pre-flash? Or you meant a more prominent difference that is as large as 0.5-1EV?

    We would like to screen out the possibility that you were referring to the small differences due to the energy reservation for the pre-flash emission.

    2.    Flash ready LED with the V6

    The second thing we found is that the flash ready LED of the SB-700 doesn't act the same way when working with the V6.

    When SB-700 is set to TTL mode and is directly connected to a Nikon camera, the flash ready LED will start blinking after firing.  That means the flash capacitor is being charged. The SB-700 allows the user to fire even if the capacitor is not fully charged and not reaches the assigned power level. It fires at the lower power compared to the set power level. When the Ready-light turns to solid light, the capacitor is fully charged. It is ready to fire as it should to the assigned power output.

    Whenever the SB-700 uses with the V6, the Ready-light stays on solid light. It doesn't tell whether the capacitor is being charged or fully charged. That may gives 2 false impressions to users:

    a.    The SB-700 does not give its full power in the last fire. It behaves as if the flash has just fired at 1/16 or lower.
    b.    As a result, the capacitor has still come with enough voltage for the next fire at full power immediately.

    Both of these false impressions may confuse us in measuring the power output of SB-700 triggered by a V6. This situation is more obvious in subsequent shooting at full power. If by looking at the flash ready LED we believe that the SB-700 is ready for another full power flash and we fire a subsequent flash immediately at full power, it may end up produces a light similar to 1/4.

    Is that similar to your experience?

    Also, please let us know in which way you measure the flash output? Is it by reviewing pictures, or by a light meter? The last thing we hope is that you wouldn’t tell whether the SB-700 was giving its full power by just observing the flash-ready LED, as it turns out to be a wrong signal when working with the V6.

    If you have a chance to test it again, after each shot please try wait for long enough for the capacitor to be fully charged. And let us know whether the problem remains.

    Meanwhile, we are working a solution in the firmware to support the flash ready LED so that it could give correct signal when working with the V6. Please allow us a little time for working on the firmware update.

    I hope the above is helpful. If you have further questions or concerns, please do not hesitate to contact us.

  • Hi,

    Thanks for all the information, it explains a lot.

    First, while I did do white-wall pictures with firmware v1.0.160 to track the output of the SB-700, I didn't with 1.0.175 and was therefore fooled by the behaviour of the flash's ready light. I've done white-wall pictures now with the latest firmware, and I can see that there is indeed reasonably consistent output changes between 1/1 and 1/4 power as I turn the power up or down in 1/3-stop increments.

    Also, 1/1 output through the combination of the V6 + TTL on the flash is only about 0.2EV less bright than the SB-700 set to manual and 1/1 dialed in there.

    So, I'd say the SB-700 and Cactus V6, with firmware v1.0.175 installed, are working pretty well together. My apologies for not properly testing this combo before posting that the pairing was still not operating properly, as I should have known better than to rely exclusively on the flash ready light.

    That said, I hope you'll be able to make the flash ready light behave normally in a future firmware update.

    -Rob Galbraith

  • Awesome!

    I'm glad to see the problem has been resolved. Definitely, the upcoming firmware will make it even better. 

    If you have concern or product suggestion, please feel free to share with us.
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