mountain bike flash photo

Hi all:

I took a quick shot of a friend mountain biking, and found that many shots had a weird ghosting effect (see helmet and handlebars). I know the photo isn't great for other reasons - but am wondering why I got the ghosting.

I used 3 flashes. I fired with a radio trigger, and 2 as optical slaves.

I am guessing either:
-ambient light is the cause
-or the flashes didn't fire at exactly the same time

Any suggestions on what is causing it?
[ATTACH]B[/ATTACH]

What shutter speed?

FarmerTed1971 wrote in post #17548000
What shutter speed?

1/60. Which I now is slow - but with limited ambient light, I thought the flash would still stop the action

I tried rear curtain sync... but to be honest, not sure if that setting even works with the optical slaves?

I am guessing here, but the optical slaves would not have flashed until the main one did. So it likely would have been ok to go with second curtain flash. I am guessing you are seeing the motion due to the slow shutter speed. Even though the flashes are the main contributor to the light source, the ambient probably still picked up the image (ghosting) when they first entered the frame and then the flash caught the stop action (clearer) piece of the image.
Again, just a guess. But I kind of like how it conveys the sense of movement in the rider. To each their own I suppose.
If you had done first curtain sych, I am guessing the ghost would be in front of the rider instead of back, so I think the second curtain sync was the correct call for this shot.

sirquack wrote in post #17548455
I am guessing here, but the optical slaves would not have flashed until the main one did. So it likely would have been ok to go with second curtain flash. I am guessing you are seeing the motion due to the slow shutter speed. Even though the flashes are the main contributor to the light source, the ambient probably still picked up the image (ghosting) when they first entered the frame and then the flash caught the stop action (clearer) piece of the image.
Again, just a guess. But I kind of like how it conveys the sense of movement in the rider. To each their own I suppose.
If you had done first curtain sych, I am guessing the ghost would be in front of the rider instead of back, so I think the second curtain sync was the correct call for this shot.

Thanks for the feedback!

The second shot has noticeable camera movement blur (especially noticeable on the branches on the left), so that probably didn't help.

If the ghosting bothers you, you could probably cut your ambient exposure by a stop or more without losing the overall effect that you are seeking, allowing you to increase the shutter speed.