Photography. Since Yi-Peng takes place at night, it is best to use a lens with a wide aperture as you need much available light to make it through the sensor - the wider the aperture, the better. My lens of choice during this festival is a 10-22mm ultra wide-angle as it focuses better in the dark and also gives consistent sharpness throughout the scene. The lens is also perfect for shots of people launching lanterns in the air. It exaggerates the arms of your subjects as they hold the lanterns before release. It is recommended that flash is not used as it destroys the light and mood of the festival, hence crank up your ISO.