iPhone 18 Pro's Variable Aperture Creates Starburst Effect
New camera feature enhances light photography with artistic flare.
1Variable aperture introduction
The iPhone 18 Pro introduces a first-of-its-kind variable aperture system in smartphones, allowing users to manually adjust the lens opening from f/1.4 to f/2.8. This mechanical innovation mimics professional DSLR cameras, providing greater creative control over depth of field and light intake. Apple engineers achieved this through a precision 9-blade iris mechanism that maintains compact form factor while enabling aperture changes in 1/3 stop increments.
2Starburst effect mechanics
When shooting bright point light sources at smaller apertures (f/2.4-f/2.8), the camera produces distinct starburst patterns with 18-point rays. This occurs as light diffracts around the aperture blades, with each blade pair creating one light streak. The effect intensifies with smaller apertures and becomes visible in both photos and videos, offering new creative possibilities for night photography and urban scenes without post-processing.
3Optical system enhancements
Apple redesigned the entire camera module to accommodate the variable aperture, including a new anti-reflective nano-coating on lens elements to maintain image quality across all aperture settings. The system automatically compensates for potential vignetting at wider apertures and chromatic aberration at smaller openings. Computational photography algorithms adjust in real-time to optimize dynamic range and sharpness based on selected aperture.
4Professional photography features
The Pro Camera app now includes an aperture priority mode and manual focus peaking to leverage the new hardware. Photographers can preview depth of field changes in real-time through the viewfinder, with haptic feedback confirming aperture adjustments. Apple claims the system can switch between extreme apertures in 0.3 seconds, faster than most mirrorless cameras, while maintaining silent operation for video.
5Low-light performance tradeoffs
While smaller apertures create artistic effects, they reduce light intake by up to 2 stops compared to maximum aperture. Apple's new Night Mode 4.0 automatically activates longer exposures and multi-frame processing when detecting small aperture use in dark environments. Early tests show the system maintains competitive low-light performance despite the light loss, with computational photography compensating for the physical limitations.
6Creative control expansion
The variable aperture system enables new creative techniques previously impossible on smartphones, including sunstars in daylight, controlled bokeh shapes, and selective focus effects. Professional cinematographers can now achieve more film-like depth transitions in video. Third-party apps will gain API access to aperture control, potentially enabling automated aperture ramping for time-lapses and other advanced techniques.
7Manufacturing challenges
Industry analysts note the variable aperture mechanism represents one of the most complex camera systems ever miniaturized for smartphones, requiring micron-level precision in moving parts. Apple reportedly developed new dust-proofing solutions and durability testing protocols to ensure reliability over 500,000 actuations. The mechanism adds approximately 0.8mm to camera module thickness compared to fixed-aperture designs.
8Mobile photography evolution
This innovation marks a significant step in smartphone cameras bridging the gap with dedicated photography equipment. By bringing professional-grade control to mobile devices, Apple continues pushing computational and optical boundaries. The starburst effect serves as both a practical tool and visible demonstration of the system's capabilities, potentially influencing competitors' future camera designs.
Original article: CNET (YouTube) — iPhone 18 Pro's Variable Aperture Creates Starburst Effect