Can I trigger shutter on camera and control lights off camera?

Started 3 months ago | Discussions thread
fotowbert Veteran Member • Posts: 3,219
Flashpoint SPT for remote shutter

kli wrote:

Don't think that would work, because of timing issues. If you cabled the Godox to the sync output on a Yongnuo transmitter unit, then the Yongnuo signal would go to the Godox lights and the shutter release on the camera at the same time. Which would be tripping the flashes too early to be caught in the image.

I think you need two Godox transmitters, one on-camera to trip the lights, one in-hand to set the power levels, and then the Yongnuo triggers to act as transmitter/receiver for the camera shutter.

Set the on-camera Godox tranmsitter's C.Fn. SHOOT to APP, and whatever power levels you set on the in-hand Godox transmitter will stick on the lights.

Or. If you live in the US, you could get a Flashpoint SPT transceiver unit from Adorama. You can cable its shutter output to the camera's shutter cable release port. And it will do the appropriate delay between tripping the shutter and firing the flashes, while serving as both shutter receiver and flash transmitter.

I appears the Flashpoint SPT transceivers are actually using separate RF channels to achieve correct shutter-flash timing.

The SPT's remote shutter receiver circuit is actuated by the next higher channel above what they are set for as explained on flashhavoc's FP SPT page where it says:

Also one issue Flashpoint ran into while developing the R2 SPT transceivers was that the shutter release unit in hand would unwantedly test fire the remote flashes early as you tried to release the camera shutter.

To avoid this the TRX mode was set up so that the shutter release remote in hand must be set to one Channel higher, than the TRX unit attached to the camera and remote flashes are set to (as illustrated below).

This way the TX in hand can not directly communicate with the remote flashes, and fire them early. Though the TX in hand can be briefly set back one Channel to directly test fire the lights while taking light meter readings, and remotely adjusting power levels.

Similar wording can be found in the FPRRR2SPT manual on Adorama's website.

YongNuo's RF-603II triggers (which I use) also allow a single unit at the camera to provide both remote shutter and flash firing with correct timing while all units can remain set to a single RF channel.

  • John
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"[If you don't sweat the details] the magic doesn't work." Brooks, F. P., The Mythical Man-Month, Addison-Wesley, 1975, page 8.

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