The pop-up flash produces notoriously bad results if it is allowed to overpower any ambient light and is used as the main light. This is because it is a small, hard light, and it is directly on the camera axis, so you can get a washed out look, particularly if you're photographic a human face - no light and shadow areas.

If you use it as fill, it can enhance your images, not harm them:

• it will add catch lights to the eyes
• it will fill in shadow areas, preventing dark eye sockets or dark shadows in the neck area. Portrait photographers often place a fill lights behind or above the camera, on-axis (true, it's a larger, softer light, but the idea is the same)

To use as fill, you simply have to dial down the power (using flash exposure compensation). As long as there is reasonable ambient light, and you only fill in shadows with the pop-up flash, you can obtain fine results.

You wouldn't want to rely on it for portrait work, but for general snapshots, with exposure dialed back a bit, it's far better to use the on-board flash than to have blurry, underexposed and noisy images.

Not all photographs are made of human faces however. Pop up flash can be very useful in macro work for example to allow you to take hand-held shots at a faster shutter speed or lower ISO.