flash or fast lens for music shots

I'm looking to get a new piece of equipment but I'm not sure weather to get a flash or a fast lens. I'm really into photography, however I don't know much about either (flash or lens). I'm starting to get really into live music photography and I want to be able to capture the picture in low lighting but I don't want to wash it out with my flash, i also want it to look like a concert not like a picture taken outside during the day.. I can't do a slow shutter speed because they're moving too fast and it comes out blurry. tri-pod isn't an option either. I was just wondering if anyone had any tips on what I would benefit more from buying and also what the differences between flashes and fast lens's are. like what's a good flash and what's not. PLEASE HELP! also just basic information about flashes would help. i've never used one so i really have no idea about them. i have an XSI

read this and get back to us if you have more questions.

With a flash you add lighting to a scene. Both quantity and quality.
With a fast lens you can capture more of the light available with a given shutterspeed / ISO.

For Performing Arts, you'd mostly want to use ambient, so a faster lens is needed.

Generally, I shoot at ISO 1600 or faster, f/2.8 or faster in smaller clubs.

Oh, and welcome to POTN

I would say go for the fast lens for what you are shooting. Flash can wash out a lot of the ambient light in these situations if used improperly and you aren't always allowed to shoot with flash where as you can always use a fast lens .

Very much an amateur here but from my experience a flash is occasionally useful, whereas a fast lens is essential (and yes you can tell from my sig I don't have a fast lens atm so haven't been shooting any gigs - soon to pick up yet another nifty fifty!).

Flash is generally not a good thing when shooting a concert, I find, even with the second curtain sync on.

Go for a fast lens. A 50mm f/stop 1.8 will only run you about 100 dollars, and comes in REALLY handy when it comes to shooting shows. (http://www.flickr.com/​photos/jessschiff/3519​482521/)

Being in a band and a photog I can say Flash is annoying when its beats on your face over and over but once in a while isn't bad, I feel it pulls the mood from your photo though, Try bouncing the flash off the ceiling or walls without directly hitting them, tends to not be as bad and it acts as a fill w/o flooding the stage lighting colors and keeps your subjects from looking incredibly colorless from the flash. You still need a fast lens regardless of flash though, 50 f/1.8 is great for the price but a bit slow on the focus you WILL lose some shots and you WILL still get some great ones, I've had best luck especially since using a crop cam w/ the sigma 30 f/1.4 and the canon 50f/1.4 yea you gotta dish out a little extra cash but you get what you pay for as do the bands that are paying for you, make it worth there while and you'll make more $$$ in the long run.

i agree entirely with madgwick, coming from the point of view of being someone in a band and a concert photographer. altho I personally have never really used a flash at a gig (once, i did a strobist setup on the stage for a friends band) because i find it distracting and quite frankly rude not so long ago i was shooting a show and the other photog was bouncing his flash off the roof and side walls, i copped it in the eyes a few times and so did the front row, and im sure we all know how fun a 580 at point blank to the eye can be just my optinion. flash is great, but leave it at home for a gig. get a fast lens.

properly used, fill flash is certainly not blinding, and not very obtrusive.