iPhone 18 Pro variable aperture: what it really changes

The iPhone 18 Pro variable aperture puts real moving blades in an iPhone's main camera for the first time, with four settings from f/1.48 to f/4. If you learned on a film camera, you'd expect that to mean big changes in background blur. It doesn't. By our estimate, even f/1.48 has the depth of field of about f/5 on a 35mm camera.

What it really buys is more light at night, and a little more say over the trade-offs the rest of the time. Here's how to think about it.

What is the variable aperture on iPhone 18 Pro?

It's a set of six laser-cut blades, each thinner than a human hair according to PetaPixel's interview with Apple, built into the 48MP Fusion Main camera. You get four settings, and the camera picks between them automatically unless you step in. The Ultra Wide and Telephoto cameras keep their fixed apertures.

The reason is less about creative control than you might think. Apple's Matt Waldon told PetaPixel that the project began with low light: "we really wanted to improve the sensitivity". A bigger sensor would have needed more space, so Apple made the lens faster instead, going from f/1.8 to f/1.48.

But a lens that fast has a cost. In some shots, Waldon explained, you'd lose sharpness in a close subject's background. So the lens needed a way to stop down, and the aperture blades were born.

What each aperture setting does

Setting	Apple's use for it	Light compared with f/1.48	Depth of field on a 35mm camera (our estimate)
f/1.48	Low light and indoor scenes	Most light	About f/5
f/1.8	Default: a balance of low light and depth	0.6 stops less	About f/6.3
f/2.8	More depth	1.8 stops less	About f/10
f/4	Maximum depth, plus starbursts	2.9 stops less	About f/14

The last column is our own sum, not Apple's. Apple lists 1.22 µm pixels on the 48MP main camera, which works out to a sensor of about 9.8 x 7.4 mm and a crop factor of about 3.5. Multiply the f-number by that and you get a rough film-camera match for depth of field at the same framing.

There's a sharpness trade-off at both ends. Waldon says you give up a little at f/1.48 because of aberrations, and a little at f/4 because of diffraction, and Apple still treats f/1.8 as the best all-rounder.

Why depth of field barely changes

If you've used a film SLR, here's the useful part. As Fstoppers' Lee Morris points out, an f-number is first an exposure setting. f/4 on an iPhone and f/4 on a 35mm camera give the same exposure, so your metering instincts carry straight over.

Depth of field is the side effect, and it depends on sensor size. Morris's example: focus at 12 feet and f/1.48 keeps everything sharp from about 6 feet to infinity. At f/4, that becomes about 3.3 feet to infinity. We ran the numbers ourselves and got the same result. Either way, a group of friends at a party is in focus.

The difference shows up when something is very close to the lens. That's the case Apple points to: a close subject and a distant background that you want to keep readable. So software blur isn't going anywhere, and neither is your 50mm f/1.4.

When to set it yourself

Automatic is the right answer most of the time. Apple says everything in Pro controls starts out that way. When you do want control, open the camera tools in the Camera app and choose Lens Aperture, or add it to the tools above the frame, then tap a value. Turn on Lens Aperture in Preserve Settings if you want it to stick.

Four times it's worth it:

1. Close-ups with a background. Use f/2.8 or f/4 to keep more of the scene readable.
2. Bright point lights. Apple suggests going manual for starbursts. That's a lens effect, not the red glow of halation, so don't confuse the two.
3. Slower shutter speeds. Stopping down lets you use a longer shutter in brighter light, which Waldon flags as useful for video and stills alike.
4. Dim rooms. If the camera hasn't opened right up on its own, f/1.48 gets you the most light.

It won't change the processed look

Here's the catch for anyone hoping manual control means a more natural photo. Apple's Jeremy Hendricks told PetaPixel that Pro controls still take advantage of the computational image pipeline. You're choosing the aperture, not switching off the merging and sharpening behind the overprocessed look.

More light does help at the start of the chain. Less amplification means less of the noise that software then has to smooth away. But the film-like qualities people chase, from highlight roll-off to stock colour, don't come from the aperture.

What about Android?

Android phones got here first, and many moved on. Samsung used a variable aperture on the Galaxy S9 and S10 before dropping it, and Fstoppers points to Huawei's P60 Pro as a close match for Apple's specs. PetaPixel notes that many companies that tried the idea stopped in later models.

Samsung may stay out for now. GSMArena reported in August, citing a Korean report, that it had decided against a variable aperture across the Galaxy S27 series, because of cost and thicker camera bumps. Samsung hasn't announced those phones, so treat that as a rumour.

If you're on Android, you aren't missing much yet. Going from the iPhone 17 Pro's f/1.78 to f/1.48 is about half a stop more light, and Morris expects most shots to look the same as last year's. That's a prediction, not a test result.

Where trycheese fits

We come at this from the other end: how little do you need to touch while you shoot? Our film looks are baked in at the shutter, and the camera controls cover the basics, like exposure, lens choice and aspect ratio. There's no live filter preview, so you stay on the scene, not the settings.

trycheese isn't out yet. It's coming to iPhone and Android together, free at launch. If you've got an iPhone 18 Pro in the meantime, shoot one close-up at f/1.48 and again at f/4. Then decide whether you'll ever leave auto.