Flash with long exposure questions!

I recently bought a flash YN560 IV, and have been doing a little bit of playing around and learning it. I also recently bought a pixel stick that is used for long exposure photography.
My friends and I went out last night and did a little bit of messing around and everytime they wanted to be apart of the shot they ended up blurred. (obviously due to long shutter speeds).
I read up today that you can "freeze" them with a flash in the photo to eliminate the blur and still get the light trails in the photos!

So my question to you guys is.
When doing this, obviously you want to light the subject up and obviously the shutter is going to be open for a while. Since the shutter is most likely going to be around 6-15 seconds. Once they are "frozen by the flash" are they free to move in the photo? Or will this create blur? Will the flash ruin any of the pixel sticks art? (I will post 1-2 example photos).
I know that we would have to start the pixel stick AFTER the flash has fired correct?

Thanks for any tips or tricks guys

Here is a few examples we did but turned out slightly blur.
http://i.imgur.com/GvC​LwHv.jpg

http://imgur.com/NbsKF​KC

Yes they are free to move in fact get them out the shot as soon as possible after the flash has fired, but you'd be better if you could get a much longer shutter time. the longer the better.

Awesome thank you a ton
Guess I know what I will be doing tonight!!

in for answers!

The amount of ghosting depends on the amount of ambient light. So in a 5 second shot a person might be captured moving where they would not in a 30 secomd shot. Keep in mind those are relative examples and not meant to be guidelines. The flash duration becomes the effective shutter speed for freezing motion, but the ambient exposure determines the amou t of ghosting.

As has been said, a "normal" shot will show movement after the flash captures the subjects.

Something you can check out, though, is setting your flash to fire at the end of your shutter capture. I don't know if your gear is able to do a "second curtain synch flash", you can check it out, what happens is the movement shows before the flash goes off and then the subject "freezes" at the end...

gonzogolf wrote in post #17644167
The amount of ghosting depends on the amount of ambient light. So in a 5 second shot a person might be captured moving where they would not in a 30 secomd shot. Keep in mind those are relative examples and not meant to be guidelines. The flash duration becomes the effective shutter speed for freezing motion, but the ambient exposure determines the amou t of ghosting.

So say I am shooting about as dark as possible. Probably some slight lighting about 200 feet away?

Jackehboy wrote in post #17644211
So say I am shooting about as dark as possible. Probably some slight lighting about 200 feet away?

As dark as possible means no ambient, so no ghosting. But some light is some light, so the risk of ghosting depends on the amount of light and your aperture and ISO. This isnt something we can answer without real data.