It's a fact that Canon PowerShot or other digital cameras need light on subjects in order to capture an image of them. OK, what if there is no light? Or what if there is not enough light? The simple solution is to turn on your PowerShot's flash.
Most of the case, your PowerShot camera is smart enough to detect the amount of light and to decide whether a flash should be turned on. For instance, when you try to take some indoor photos, the flash is usually on automatically since there is not enough light to maintain the decent speed of shutter. When you fire the flash, subjects will suddenly receive fair amount of light. In other words, the light density is dramatically increased for a short period of time. Therefore, the camera can capture images by using high shutter speed. Because some compact cameras' flash is not enough to sustain fast shutter speed, so, one thing to keep in mind is you have to hold your camera tightly although the flash is turned on.
Basically, with the Canon PowerShot camera, you can three setting for flash: Auto, Turn on, and Turn off. Their meaning is so simple. Auto is to let your PowerShot decide whether or not the flash should be fired. Turn on is to force the flash to fire. Turn off is to always shut the flash off.
For most of situations, you can trust your camera about the flash. Thus, just leave the setting at Auto. However, when you want backlight photographing, you may have to use the Turn on option. The reason is because there is a lot of light behind your subject. So, the camera might think that there is enough light, and, of course, the flash is not fired. The result is the subject will be too dark.
When you try to take a night scene, you should turn the flash off. There are 2 reasons for that. First, using flash for night scene will not help much, so it wastes battery for nothing. Second, for close-up shots, the subjects will be too much white from flash light, and for wide angle view, your flash doesn't help much (like in the first reason). Another use of Turn off setting is when you're in places that don't allow flash like theaters or picture galleries.
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