Sports Flash

[Gobae]

Although I've shot quite a bit I don't do a whole lot with flash, but I've just started shooting Roller Derby and would like some help with an idea I'm trying to suss out.

Typically I shoot bouts at 1/320 or higher as this seems to freeze the action nicely. However, some venues are poorly lit and force me to increase my ISO to 1600 (without flash) in order to maintain 1/320 and on my D90. This is about the max I like given the amount of noise/grain I find acceptable. Since the maximum flash sync is 1/250 for the D90 would I really gain anything by backing the shutter speed down to 1/250 and using flash? In other words, if I use ISO 1600, 1/250, AND flash will I gain anything? Or will the image be subject to the same motion blur as if I shot at 1/250 without flash?

I hope this question makes sense. Thanks!

 

[Fred Kingston_RIP]

I'm pretty sure your flash's speed will stop action pretty well clear down to 1/60... at that point, the shutter isn't stopping the action, the flash is...

You should setup a test case... Start at 1/250 or 1/200 (your sync speed for the D90), set ISO to 100 and start around f5.6... or whichever Fstop you like using... start decreasing your shutter downward to where you get acceptably sharp images... once you've dialed in the speed, then start increasing the ISO if you need to...

 

[nickt]

Flash will freeze pretty much everything if it can reach. But if the settings used with the flash could cause a noticeable exposure without the flash, then you might get a freeze from the flash + a blur from the ambient light part of the exposure. The blur will be in the wrong direction, but that is another story. The trick would be to lower the ambient light exposure slightly so the flash is the only significant light. Wayne can explain this better, I'm sure he will stop by. Check out his website on this:
Flash pictures are Double Exposures- Outdoors

This might help too for figuring if your flash will reach:
Understanding Guide Numbers, including GN Calculator