If you want to take a snapshot in regular light, you can turn off the flash. If you need to take a snapshot quickly, you can turn off the 3 second countdown. You can also turn off both.
To turn off the countdown, press the Option key while clicking the Shutter button.
To turn off the flash, press the Shift key while clicking the Shutter button.
To turn off both the countdown and flash, press Option-Shift while clicking the Shutter button.