iPhone 18 Pro wider aperture makes small blur change

iPhone 18 Pro has new lens with wider opening. Apple uses f/1.48 for blur. iPhone 17 Pro had f/1.78. F/1.8 is second widest on iPhone 18 Pro. Test photos use same distance and framing. Same main camera with variable lens. Photos taken at same distance. Subject and person stood still. Gap of few seconds between shots. Close shots show background blur. Blur seen from 8 to 70 feet away. Fountain closest at 8 to 10 feet. Tree at 30 feet shows small change. Pagoda at 70 feet blur stays clear. Bridge and buildings far blur less. With f/1.78 blur is weak in some spots. With f/1.48 blur is stronger. Small change helps business photos.