A variable aperture is the biggest change to an iPhone camera in years, and it will change a narrower set of your photographs than the marketing implies. Apple’s iPhone 18 Pro moves the 48MP Fusion main camera from a fixed lens to one with four stops, f/1.48, f/1.8, f/2.8 and f/4.0, driven by six laser-cut blades, and it leaves the other three cameras exactly as they were.
Work through Apple’s own numbers and the picture is clear enough to make a buying decision on. The widest setting gathers roughly 45 percent more light than the fixed f/1.78 lens in the iPhone 17 Pro, which is about half a stop, and the full range from f/1.48 to f/4.0 spans a little under three stops. That is real, and it is not the difference between a snapshot and a portfolio piece.
Key facts: what the variable aperture is, and is not
| Item | What Apple published |
|---|---|
| Camera affected | 48MP Fusion Main only, 24 mm |
| Stops | f/1.48, f/1.8, f/2.8, f/4.0 |
| Mechanism | Six laser-cut blades |
| Manual control | Aperture and shutter speed settings in the Camera app |
| Ultra Wide | 48MP, 13 mm, fixed f/2.2 |
| Telephoto | 48MP, 100 mm, fixed f/2.8 |
| Front camera | 18MP Center Stage, fixed f/1.9 |
| Previous generation | iPhone 17 Pro and 16 Pro main camera fixed at f/1.78 |
What half a stop of extra light is actually worth
| Aperture | Light relative to f/4.0 | Difference from f/1.78 |
|---|---|---|
| f/1.48 | About 7.3x | About 45 percent more light |
| f/1.8 | About 4.9x | Roughly the same |
| f/2.8 | About 2x | About 60 percent less light |
| f/4.0 | 1x | About 80 percent less light |
Those ratios are our arithmetic on the f-numbers Apple published, since light gathered scales with the square of the aperture ratio. Read the first row carefully. Going from f/1.78 to f/1.48 is worth about half a stop, which in practice is one step of shutter speed or a small reduction in the sensitivity the phone has to use indoors.
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The bottom row is the more interesting one. Nothing on an iPhone could previously stop down to f/4.0 by choice, and that is what makes this a photographer’s feature rather than a low-light feature. It gives you a way to hold more of a scene in focus, and a way to slow the shutter in bright light without a filter.
The three cameras that did not change
Apple has not announced any change to the Ultra Wide, the telephoto or the front camera on this generation. The Ultra Wide stays at 48MP and f/2.2, the telephoto at 48MP and f/2.8, and the front camera at 18MP and f/1.9.
That matters for how you read the headline. Three of the four framings on the phone, including every shot past 2x and every selfie, are optically identical to last year’s. The variable aperture applies to the 24 mm main camera and to the 12MP 2x crop taken from it, and nowhere else. Our camera explainer walks through the full lens set.
The pictures this should change
- Portraits at f/1.48, where you want the shallowest optical separation the phone can produce rather than a computed depth map.
- Group shots and landscapes at f/2.8 or f/4.0, where the old fixed lens forced you to rely on distance and focus stacking to keep faces at the back of a group sharp.
- Bright daylight video, where stopping down lets you keep a slower shutter for natural motion blur instead of the clipped look of a very fast one.
- Indoor and evening frames at f/1.48, where roughly 45 percent more light is a real gain even if it is a modest one.
What it should not change is the ordinary daylight photograph. At sensible light levels the phone was already stopping the picture down through computation, and Apple’s Photographic Styles, Night mode and Smart HDR pipeline still do most of the visible work.
Why nobody can tell you how much better it looks yet
Aperture blades move light. They do not move a sensor, and Apple has not published the sensor size or pixel pitch for the iPhone 18 Pro, which is the figure that would tell you how much of the shallow-focus effect is optical rather than computed. No reviewer has shot with this camera, so any claim about how the f/1.48 setting renders a background, or how sharp the corners are at f/4.0, is a guess.
The one thing that is not a guess is control. Apple has put aperture and shutter speed into the Camera app as manual settings, and a photographer who wants to decide those two things instead of accepting Apple’s choice now can. Whether you want that is a better buying question than whether the pictures look 45 percent brighter.
What Apple has not said
Apple has published the four aperture values and the blade count and little else. There is no sensor size, no published shutter speed range, no statement on whether the aperture can be set independently in video, and no sample comparison against the fixed f/1.78 lens it replaces. Apple has also not said whether third-party camera apps can set the aperture.
The iPhone 18 Pro goes on pre-order at 5 a.m. PT on Saturday, September 12 and reaches buyers on Friday, September 18. That is the first date anyone outside Apple will be able to shoot the same scene at f/1.48 and f/4.0 and say which one they would keep. Our iPhone 18 Pro announcement roundup has the rest of the specification, and the event recap covers everything else Apple showed.
