iFixit and YouTube content creator JerryRigEverything have shown in separate videos that placing a magnet near the main camera sensor of the iPhone 18 Pro can cause its variable aperture to close automatically. The iPhone 18 Pro is notable for being the first iPhone to feature a 48-megapixel main sensor with a variable aperture, which adjusts the size of the opening that lets light in. This aperture is controlled by six thin blades that open and close to regulate light intake, ranging from f/1.48 (wide open) to f/4 (more closed). This is a significant change from earlier models like the iPhone 17 Pro and iPhone 17 Pro Max, which had a fixed aperture and were released in September 2025. The movement of these blades is controlled by small electromagnets, similar to those used for optical image stabilization, but the two systems are independent. iFixit tested this behavior by exposing a disassembled camera module to a magnet, and JerryRigEverything demonstrated the same effect on an intact iPhone. The results show that external magnets can influence the aperture blades, even though this isn't usually a problem for most users. While the iPhone 18 Pro's camera is designed to be robust, users are advised to be cautious with strong or improperly placed magnets, such as those found in some phone cases, car mounts, or magnetic accessories. Repeated exposure to such magnets might lead to the blades becoming stuck or misaligned, which could require the replacement of the entire camera module. According to Apple, the cost of replacing the camera module is estimated at around 299 euros. Apple had already warned users about the sensitivity of optical stabilization and autofocus to magnetic fields before the iPhone 18 Pro was released. These warnings were included in an official support page, highlighting the importance of being aware of the device’s interaction with magnetic materials. While the iPhone 18 Pro's variable aperture is an innovative feature, users should take care to avoid potential issues caused by external magnetic interference.