The dreaded pop-up flash. A professional photographer's nightmare.
The problem with the flash attached to most camera bodies is that it basically pops a big old FLASH of FAKE light right at your subject. While studio lighting can be unbelievably fantastic given the right circumstances, a flash like the one attached to a camera body is not ideal.
For kicks, I shot the exact same subject in the exact same light (frame after frame)- the first with the light in my house (from both a window and lamps) and the second with the same lighting conditions + pop-up flash. These are both SOOC (straight out of camera)
As you can see, the second looks completely washed out. His skin looks pale and NOTHING is the right color. You can see odd shadows between him and the chair and it's quite clear the flash changed his expression to boot.
So here's the deal: I had to TURN ON my flash. Because I shoot with my camera manually, I have that control. I don't normally shoot with flash, EVER. Why? I don't need it. There is plenty of light and my camera is built to expose for light, but I have to SEE it. Some locations have more/"better" light than others. Yes, I take snapshots when the light isn't ideal. I push my camera's limits and it's always worth it. For clients.. even if I get to a location and the light isn't ideal, I have to find it and work with it! That's my job. But I still never use my pop-up flash.
So how do you keep your flash from firing?
On an SLR camera.. read your manual. They're all different. If you shoot in manual, it should be off automatically and you will have to press a button to turn it on.
On a point and shoot camera.. read your manual. There is a button usually that has a little lightning bolt and if you press that, it will rotate between flash options. The problem with turning off your flash on a P&S camera is that the shutter is never going to be as quick as on an SLR camera so if you are shooting a moving subject in a low-light situation, you will likely have less control not only over shutter speed but the shutter release. This can mean that indoors, you simply won't get a photo without motion blur inside without your pop-up flash. If you have to use it to avoid a blurry photo, do it.
When it comes to my snapshots, I'd rather have a flashy photo than a blurry photo. When it comes to my clients, I'll give neither.