How much does a flash help outdoors?

[jammsp]

Hi Guys, I'm new to this forum. I've been searching the web for an answer to a question but have found nothing useful - so where better than a forum of photographers!..

I shoot alot of motorsport. I use a Canon 1D mark ii with a 100-400mm f4.5-5.6 L lens. It's a cracking combo but when the light drops, some of you may know, the 100-400mm struggles a wee bit and the 1D mark ii's ISO performance isn't great (Compared to what is possible now).

I was wondering weather a flash (e.g. 430 EX) will help, but will a flash make an difference when shooting long distance, at 400mm, on an overcast day? Or will it be wasted when shooting long distance?

I've seen lots of people saying how it helps for indoor sport and sports in which you can get close up, but nothing on motorsport/karting.

 

[Gr8Shot]

Flashes do nothing over about 5m away when outdoors.

 

[Phil V]

Flash and motorsport is contentious, with some people saying it'll distract the drivers and others saying it doesn't.

If you do decide to use it, you can avoid the distance limitation and ugly light by going wireless. So the flash can go close to the track, using less power (faster recycling) and giving some direction / shadow. An external power pack will allow short bursts of flash at higher ISO's too. I had a play on rally GB last year, but without an external power pack, had limited success on a jump in the early morning.