A mode, which stands for Aperture Priority allows you to select the f/stop you wish to use, while the camera selects the appropriate shutter speed based on its metering of the ambient light. The f/stop you choose could be based on the amount of depth of field you wish to have in your subject. The shutter speed chosen by the camera is designed to accommodate the aperture you have chosen. It could range from 30 seconds to the faster flash sync speed. This is an important consideration, since too slow of a shutter speed could require a tripod to avoid movement and blur.The content you are trying to access is only available to members. Sorry.