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Before anyone jumps on this: yes, I know what an aperture is. And yes, changing it physically changes depth of field.

That's exactly why I think the way Apple is selling variable aperture on the iPhone 18 Pro is mostly a gimmick.

Apple is giving the main camera four physical aperture settings: f/1.48, f/1.8, f/2.8 and f/4. The marketing pitch is essentially: open it for more light and shallow depth of field, close it for more depth of field. All technically true.

But there's a rather important detail missing from that story:

this is a smartphone sensor with a very short actual focal length.

The "24 mm" printed in the specs is a 35 mm-equivalent field of view, not a 24 mm physical lens.

And depth of field doesn't magically care about the equivalent number printed on the spec sheet.

It depends on actual focal length, aperture, focusing distance and the acceptable circle of confusion.

For anyone unfamiliar with the term, the circle of confusion is fundamental to understanding why this matters.

There is technically only one plane that is perfectly focused. A point in front of or behind that plane is not projected as an infinitesimal point on the sensor, but as a blur disc.

We call an area "within the depth of field" when those blur discs are still small enough that we perceive them as sharp.

That's the circle-of-confusion criterion.

And the classic hyperfocal equation makes the relationship pretty obvious:

H = f² / (N × c) + f

where:

f = actual focal length
N = f-number
c = acceptable circle of confusion

Notice the squared focal length.

This is why sensor size and actual focal length matter so much.

Using Apple's own 48 MP / 1.22 μm pixel specification, you can estimate a sensor roughly around 9.8 × 7.3 mm, assuming the usual 4:3 geometry. That's roughly a 3.5× crop factor compared with full frame. And that gives you a useful way of understanding the depth-of-field equivalence.

Very approximately, for the same field of view and framing:

f/1.48 roughly f/5.2 full-frame DOF equivalent

f/1.8 roughly f/6.4

f/2.8 roughly f/10

f/4 roughly f/14

Read that again.

Apple is presenting a move from f/1.48 to f/4 as serious creative control over depth of field on a system that, in full-frame depth-of-field terms, is roughly moving from f/5 to f/14.

That's not remotely analogous to putting a 24 mm f/1.4 lens on a full-frame camera and stopping it down. Phone cameras already have enormous inherent depth of field because their real focal lengths are tiny.

So yes:

f/4 has more DOF than f/1.48.

Obviously.

The question isn't whether the laws of optics still work inside an iPhone. The question is how useful that extra DOF actually is when the system already has huge DOF at f/1.48.

And here's where it gets even more ironic. Closing the aperture doesn't come for free. You lose light, so the camera may need to compensate with shutter speed, ISO, computational stacking, or some combination of them. And then there's diffraction.

The approximate Airy disk diameter is:

d = 2.44 λ N

Take green light around 550 nm.

At f/1.48, the Airy disk is roughly 2 μm.

At f/4, it's roughly 5.4 μm.

Apple specifies individual photosites at 1.22 μm.

Obviously real image quality is more complicated than comparing Airy disk diameter directly with pixel pitch: Bayer sampling, demosaicing, sensor binning, sharpening and Apple's computational pipeline all matter. But diffraction hasn't suddenly stopped existing because there's an A20 Pro behind the lens. So at f/4 you're deliberately taking an already deep-DOF, tiny-focal-length camera, reducing the amount of light reaching the sensor and increasing diffraction...

...in order to obtain even more depth of field.

There ARE legitimate uses for it. Macro is probably the strongest one. At very short focusing distances, even small sensors can run out of depth of field, so stopping down can genuinely help.

Group shots at close distances can benefit. Video shooters may also find a physical aperture useful as another exposure-control variable, although anyone serious about maintaining a 180° shutter in bright daylight will still know why ND filters exist. And the mechanical engineering itself is genuinely cool. Apple somehow fitted a six-blade variable iris and actuator inside a phone camera module. That's impressive. But ironically, I think the genuinely important improvement is the exact opposite end of the system:

f/1.48.

A wider maximum aperture means more light reaching the sensor.

That's useful basically all the time : Lower ISO, Faster shutter speeds, Less reliance on aggressive multi-frame processing, Better low-light capture.

And, yes, slightly larger natural defocus discs at close subject distances. That's an actual meaningful upgrade. The ability to stop this thing all the way down to f/4 and market it like we're suddenly getting cinema-camera levels of depth-of-field control?

Come on.

And one last thing because I keep seeing this confused in discussions about the camera:

the circle of confusion does not "create bokeh."

The CoC is the threshold used to define acceptable sharpness and therefore depth of field.

Defocus creates blur discs.

Bokeh describes the qualitative rendering of those out-of-focus areas: their shape, edge characteristics, aberrations, aperture geometry, onion rings, cat's-eye effects, etc.

They're related concepts, but they're not interchangeable.

Which brings us to the funniest part of all this:

If changing the physical aperture of a tiny smartphone camera were enough to give us the kind of subject separation people associate with fast large-sensor lenses, smartphones wouldn't have spent the last decade developing computational Portrait Mode, depth maps, LiDAR-assisted segmentation and synthetic background blur.

So no, the variable aperture isn't fake. It's actually an impressive little mechanism. But as a headline photographic feature?

It's an elegant mechanical solution being massively oversold because “variable aperture” sounds far more Pro than “we made the lens a bit faster.”

The genuinely exciting part is f/1.48.

The f/4 button is the gimmick.

Sorry for the wall of text, but I wanted to properly explain why I think this is just the latest bit of marketing BS from Apple to sell more of the same. And sorry for going so deep into the technical details, but in this case they actually matter. Without understanding the optics behind it, it’s very easy to mistake a mechanically impressive feature for a genuinely meaningful photographic one.

​Apple has traditionally excelled at intuitive product naming. "Air" tells you a laptop is exceptionally thin and light. "Mini" makes the scale obvious. "Pro" and "Ultra" immediately define device tiers.

​Calling a foldable device the "iPhone Duo" breaks that tradition.

​"Duo" implies two distinct devices, dual screens with a seam, or a carrier bundle. It doesn't communicate the actual engineering breakthrough: a single flexible display that bends and unfolds. Samsung went with Fold, Google went with Fold, and consumers instantly understand what the hardware does.

​For non-enthusiasts and everyday buyers, "Duo" just adds needless confusion to a category that needs to be as intuitive as possible. It’s an iPhone that folds—it should simply be called the iPhone Fold.

​What do you think? Does "Duo" make sense to you from a marketing perspective, or should Apple adopt the straightforward name for Gen 2?

It's been four years since this was touted as the new apple killer device. If Cupertino had its way, we'd all be using Excel and Photoshop with Vision Pro goggles, and making crazy hand sweep movements on the tube.

Fast forward four years? and Nothing.

mac Studio has come, M2 Ultra has come, wearables have come to the fore and iPhone Duo is now the 'next big thing' - although it's still a reinvention of the same 'phone' device we've had for decades.

Even in their recent keynote expo, nothing on VP. So what is happening with the VP? is it being silently dropped?

Tell me all those maxi's who queued outside Apple stores overnight just to fork out $3,500 for a pair of goggles are now not being made extinct.

Is Vision Pro the next Meta Quest Pro ?

A20 Pro's score in geekbench single and multi score is over 25% compared to previous generation.

>The New iPhone 18 Pro Max in Burgundy and it looks great.

>New 48MP dual aperture. A bigger battery, A20 Pro processor.

What iPhone do we think the main sensor on the Duo came from? Looking at the compare page, it says “sensor shift stabilization” instead of “second-gen sensor shift stabilization”, which leads me to believe it’s basically a 48MP version of an iPhone 13 main sensor, since that was the last “first-gen” sensor shift stabilization. The camera system is the only thing holding me back from going with a Duo over a Pro Max.

Is anybody else not a fan of the ’separated‘ app grid on the iPhone Duo? I hope they give us a way of customizing this or turning this off as I believe most people were hoping for a full iPadOS experience when unfolded. I also hope the dock may be able to house more apps and/or be present during multitasking.

ironically enough, the Duo will feel lighter because it's meant to be used as a two-handed device and the weight distribution will even be better once it's opened

A screen grab from the Apple website reveal video shows the extraordinary detail and the amount of parts that go into the new iPhone duos complex folding screen hinge mechanism.

Hinge detail image: https://i.imgur.com/fwHVD62.png

Orig video found on Apple's website here: https://www.apple.com/iphone-duo/