Originally posted by flyer Use 100 ISO with an aperture of 8 or 11 with a shutter speed of 1/180, and the bar lighting will become irrelevant. That will make it about 8 stops above your set up, so the background will be almost black and anything and everything will fade into darkness.
I've been trying to put my two cents in for hours but I keep getting side tracked.
I agree with Flyer but I'd like to add a couple things. Front curtain sync is default on my (and most) cameras. Yes I use Nikon DSLRs (FinePix actually) and I usually confine my opinions to the Pentax film forums.
Front curtain sync causes trails forward of the moving object. Not an issue if the only light is from your speedlight. If you have any ambient, the forward trails ruin the movement of the shot. So, rear curtain or slow sync is better for this.
Using aperture and low ISO to block out light would be one approach.
You could also try setting the aperture for overall IQ. Like maybe 5.6 or whatever is optimal on your lens. You would have to be a bit more careful about DOF.
You could slow the shutter down or raise the ISO (or both) to allow more ambient in so you have some background detail. The flash would still freeze the dart and the thrower.
My Nikon speedlight fires a little faster then 1/1000 at full power. The milliseconds go down in proportion to output. I have a high speed sync function (up to 1/8000) but flash power goes way down. Instead of firing once, you get a burst to eliminate shadow from either front or rear curtain.
I'm pretty sure Pentax does the same thing but, in any case, a speedlight will freeze a dart in mid air, provided you can nail your focus and time your shot.
I would like to see the captures, however the OP decides to approach this one. There are a couple different angles you could come at it.