In this shot, notice the illumination from the sun, and the illumination from the flash unit on my camera. This is one of those occasions where I needed to use the flash in order to illuminate the inside of the flower.

If you plan on doing macro photography using a built-in flash for most of your pictures, make sure your camera is fully charged. Regardless of the camera used, you'll only get to take half or less than half the total number of shots per charge. Using an external flash unit alleviates the problem since they use their own power source (said power source should also be fully charged).