Okay, several have PM'ed me questions and I cannot figure out the off-board messaging system here. So here are the photos and some building it explanations.|
Radio Shack sells the Arduino microprocessor I used for about $25. They also sell a plug-in that fits on top called a "Relay Shield" (~$20) which is four relays. You can see them stacked inside the box in the "Insides 2" photo. On top of that I made up a 10K resistor pull-up board for the Nikon shutter button, but later found out it wasn't needed as that stuff is in the Ardunios. Since Radio Shack might be going out of business, you might find the stuff cheaper.
How it works:
The Nikon shutter button I had triggers the microprocessor to trip a relay. That relay is in parallel through the cord to the Shutter Button switch inside the DJI RC box (That jack on the back in the photos at the top of this thread.) so the RC tells the drone camera to fire instead of me pressing the button on the RC box.
When the relay trigger is sent, it times out to trip the second relay by 175 ms in the software in the Arduino to short out the hot-shoe or the plug to my wireless trigger to the flash units. That puts the flash in sync with the P4's shutter lag due to the time it takes for the P4 camera to trip and use the rolling shutter to cover the frame.
Not that hard to do other than wiring into the DJI box's tiny shutter button. The programming is Arduino "Sketch" and they have a lot of people on the forum to pick info out of. Just a simple delay to the hot shoe or wireless trigger is all that's needed. I played around with the programming by flashing the LED's on the relay board to get the relays figured out.
There is, or was, something called a "Camera Axe" that was sold and maybe still is that uses a lot of flash timing abilities for water drops, flash sequencing, etc. I think the guy sold it as a DIY kit or pre-assembled. Same principle as mine, just his is adjustable without having to plug into a stand-alone computer to load the software into the Arduino via that white USB port in the end of it.
The black square thing inside is a couple of LiPo's in series tapped up so it runs on 7.4 volts. Most all the hardware, boxes, batteries, switches, etc. I got out of "All Electronics" in Los Angeles.