Outdoor concert (afro punk festival)

[Tashabelle]

is it still bad to use flash at an outdoor venue ?
And what flash would you suggest i thought i should buy one.
i only shoot with a 18-55mm lens. (canon d1000)

[bacchanal]

1) It depends on the rules (if any apply)
2) It depends on your technique
3) It depends on the lighting

A little fill flash could certainly be handy at a daytime concert or even at night depending on the lighting. Also, the flash may enable you to preserve some blue sky (lower ambient exposure + flash exposure for subject).
Generally, night time shows are pretty well lit...but with a kit lens + D1000 + fast moving subjects...I could see flash possibly being useful.

Personally, I would get a 430exII, if you plan on getting a flash. But if you have to go cheap, you might give a YN-468 (ebay) a try.

Of course, it may be expecting too much to expect to get decent results at a concert if you're new to flash photography.

[Tashabelle]

im not "new" to flash per say. i've done a tone of local bands and i just used to built in flash but usually held it completely down so very little comes though.

defusers i dont know much about. are they more portrait photography ?

[bacchanal]

Diffusers won't do much if you don't have anything to bounce the light off of (walls/ceilings etc). They can get the light source a little further away from the lens, but they won't make much difference outdoors, and they will rob you of flash power.

The main things that matter with lighting are:
1) position of light source (where the shadows/highlights are)
2) size of light source (how hard or soft the shadows are)
3) direction of light source (esp if you're bouncing, thus creating a secondary light source)

A diffuser may or may not have much effect on your light depending on how/where it's used.

[MMX]

First of all buy some better lens. If you add flash to 18-55 it will look like a photo from a P&S camera, only less noisy.
Btw if it´s punk festival, there should be no rules :D