Triggering External Flash with pi

[MattLR]

I own 2 YN560-II external flashes for my canon camera and would like to trigger them simultaneously using python on the pi. Any ideas on the simplest way i could do this?

Cheers
Matt

[PiGraham]

Xenon strobes won't work with the Pi camera because it has a rolling shutter. This means that it doesn't expose the pixels at the same time. It's a bit like using an SLR at a shutter speed faster than flash sync. You will get images with only part illuminated.

Of course every pixel will be illuminated, but not all lit pixels will be in the same output image.Simple answer is it doesn't work.

You can use an LED flash with the Pi camera if you turn it on before exposure and turn it off after a full frame has been captured (Like LED flash on a smart phone).

[P_Monty]

If you're looking to trigger the flashes for use with your regular camera, then I can see no reason why it can't be done. You'll need some form of electronic switch (eg thyristor or transistor) driven (probably via a buffer) by a gpio pin.

[PiGraham]

Good point P Monty, the Pi can trigger a 'normal' camera.

Many cameras allow a remote shutter switch control to activate the camera, and a hotshoe for a flash.
Pi GPIO could drive a transistor to short the remote shutter contact. The camera will take care of flash synchronisation.

You can also use a camera with long shutter time or Bulb setting to capture multiple strobe flashes, in dark conditions. That can be used to freeze motion as in waterdrop photos.

See this blog post:
http://www.raspberrypi.org/water-droplet-photography/

[PiGraham]

If you only want to fire multiple flash guns simultaneously simply wire the flash triggers together. You can get hot shoe cables, cut the PC Sync connectors off and twist the wires together (centre wire to centre and screen wire to screen).

You can also get slave flash triggers that detect the flash of one strobe and fire another in response.These are the easiest set-up to connect.

[MattLR]

Hi guys, thanks for the responses. I should of mentioned I'm using a canon 60d. With my current setup (water drop photography) I'm using 3 yn-622c triggers. However, even though the delay between the two is so minimal, it is still visible in my photos. Therefore, I'm just looking for a way to trigger them simultaneously with no delay at all.

[PiGraham]

Your best option is to wire the two in parallel.You can't get more simultaneous than that.

[MattLR]

Thanks for the help and tips but I discovered that somebody else experiencing the same issue found that one of their speedlites had been tampered with before purchased. As I didn't purchase my flash guns at the same time/place, this could be the case. I'm going to sell my current flashes and uprade to the new yn560-iv 's. Won't cost me much :p