Night mode is an automatic setting which takes advantage of the new wide-angle camera that's in the iPhone 11 and 11 Pro models. It's equipped with a larger sensor that is able to let in more light, allowing for brighter photos when the light is low.
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Photos of Top Strip of iPhone 5S Rear Shell Again Point to Dual-LED Flash
Notably, the space for the flash modules on the top strip appear to have spacing for a dual-LED flash, which is consistent with a December 2012 prototype iPhone 5S that leaked back in June. A dual-LED flash would improve the performance of the iPhone's flash, creating better lit, less harsh flash photos in low light conditions.
Yesterday, a report surfaced claiming that the rear camera on the iPhone 5S would retain the same 8-megapixel resolution found in its predecessor, but will feature a wider f/2.0 aperture to capture more light while taking photos. Apple will reportedly unveil the next-generation iPhone on September 10, but it is still unclear whether the event will focus singularly on the iPhone 5S or include the announcement of the lower-cost iPhone as well.