The iPhone 18 Pro’s 48MP Fusion Main camera has four aperture stops: f/1.48, f/1.8, f/2.8 and f/4.0. Apple’s tech specs list those four values for the 24 mm main lens on both the 6.3-inch and 6.9-inch models, and Apple’s press release says the aperture uses six laser-cut blades with manual control in the Camera app.
This is the first iPhone with a variable aperture, so most buyers have never had to choose an f-stop on a phone. Our variable aperture explainer covers the mechanism; this guide is about which of the four stops to pick and when.
What the four stops mean
A lower f-number means a wider opening, more light and a shallower depth of field. A higher f-number means a smaller opening, less light and more of the scene in focus. Between f/1.48 and f/4.0 the opening area shrinks by a factor of roughly seven, based on the ratio of the two numbers squared.
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| Stop | Light versus f/1.48 | Depth of field | Best for |
|---|---|---|---|
| f/1.48 | Baseline (widest) | Shallowest | Low light, single-subject portraits |
| f/1.8 | About two thirds | Shallow | Portraits with a little more sharpness |
| f/2.8 | About a quarter | Moderate | Small groups, street, general daylight |
| f/4.0 | About one seventh | Deepest | Landscapes, architecture, large groups |
The light figures are our arithmetic from Apple’s published f-numbers, not an Apple claim. Apple’s tech specs give the four stops and nothing about exposure behavior at each, so treat the middle column as a guide to how much the camera has to compensate with shutter speed or ISO.
f/1.48: low light and portraits
This is the widest stop and the one the Camera app will lean on after dark. It lets in the most light, which keeps shutter speeds shorter and pairs with the faster Night mode that Apple’s press release lists for the iPhone 18 Pro.
It is also the stop for the strongest natural background blur. The trade-off is that focus is unforgiving: with a subject close to the lens, eyes can be sharp while ears are not, so it suits a single face or object rather than a group.
f/1.8 and f/2.8: the middle ground
The f/1.8 stop gives up a little light for a slightly deeper focus zone, which makes it a safer portrait setting when the subject is moving or when two people stand at slightly different distances.
The f/2.8 stop is the general-purpose choice in daylight. It matches the fixed aperture of the 100 mm telephoto lens listed in Apple’s tech specs, so switching between the 1x and 4x cameras at f/2.8 keeps the look consistent. Street scenes, food and small groups sit comfortably here.
f/4.0: landscapes and everything sharp
The smallest stop is for scenes where you want the foreground and the horizon both in focus: landscapes, buildings, wide group photos and product shots on a table. It needs the most light, so use it outdoors or with the phone braced.
Apple’s own sample images contrast this with the wide-open look: one frame with a single sharp subject and a soft background, another with everything in the scene sharp. That pairing is the simplest way to think about the two ends of the range.
How to choose, and what Apple has not said
- Night, one subject: f/1.48
- Daylight portrait: f/1.8
- Daylight, small group or street: f/2.8
- Landscape or large group: f/4.0
- Not sure: leave the aperture on automatic and let the Camera app pick
Apple’s press release confirms a manual aperture control alongside manual shutter speed in the Camera app, plus Smart Focus subject tracking. Apple has not published which stop the automatic mode chooses in a given scene, whether intermediate values between the four stops are available, or whether the aperture setting carries over to video.
The Ultra Wide (f/2.2) and 4x telephoto (f/2.8) are fixed-aperture lenses, so the four stops apply only at 1x and the 2x crop taken from the main sensor. For how the full lens set compares with last year, see our iPhone 18 Pro vs iPhone 17 Pro breakdown. Pre-orders open Saturday, September 12 at 5 a.m. PT, and the phones arrive Friday, September 18.
