Scoping out the new iPhone camera

Oppo research regarding the 15 Pro Max's periscope

It's iPhone launch day, which means last-minute speculation over what's about to get announced. This year, as usual, I'm most interested in the camera hardware.

According to almost all reporting, including from trustworthy soothsayer Ming-chi Kuo at TF International Securities, this is the year that Apple will introduce a periscope telephoto camera to the iPhone lineup. This allows for a longer focal length — more zoom, essentially — than you'd otherwise be able to fit into even the hefty camera bumps we see today.

Kuo is usually reliable, but his reporting on the technical details so far raises more than a few questions. Here’s how the ever-helpful MacRumors summarises the expectations so far:

New periscope camera technology will be introduced with the launch of the iPhone 15 Pro lineup, but the update will be limited to the iPhone 15 Pro Max. The addition of the periscope lens to the 15 Pro Max will mark one of the few times that Apple has limited new technologies to the larger 6.7-inch Pro iPhone, using an inferior feature in the standard 6.1-inch Pro iPhone.

The periscope lens system will be used for the telephoto camera in the iPhone 15 Pro Max, allowing for 5x or 6x optical zoom. Comparatively, the iPhone 14 Pro Max offers 3x optical zoom, which we're also expecting for the iPhone 15 Pro.

And here’s Bloomberg’s Mark Gurman in his Power On newsletter this week:

Apple also is adding an extra enticement to the top-of-the-line Pro Max: The phone will offer a wider range of optical zoom via a so-called periscope lens. This system doubles the iPhone’s ability to zoom in on an object via the hardware lens from 3x to about 6x.

Periscope lenses are a way to fit longer telephoto cameras into smartphones. They make use of the length of a phone rather than being constrained by its lack of depth.

To over-simplify centuries of photography, cameras work by focusing light on a flat surface, which is where you get your photo. That generally used to mean placing a lens in front of film, and these days it means putting a lens in front of an image sensor. In the case of a smartphone, that sensor is aligned laterally with the back of the device, as if you were placing a tiny postage stamp on the motherboard. Several pieces of glass or plastic are then stacked on top to create the lens.

To simplify again, the more glass you can put in front of that flat surface, the better your ceiling for image quality. The distance between the sensor and the outermost lens element is the biggest limiting factor when it comes to optical design. That's why phone camera bumps have continued to increase in size.

The Oppo Find X6 Pro. Periscope lenses have distinctively rectangular optics, unlike conventionally circular glass.

Lenses with an equivalent focal length of between 28mm, which is close to a typical default smartphone view, and 50mm, which is roughly a 2x zoom from that point, are usually the easiest to build. That's why ultrawide lenses were considered to be exotic products before they showed up on smartphones, and why pro-level telephoto lenses stick out from pro-level cameras at pro-level sporting events.

It's also why supertelephoto focal lengths have been impractical on smartphones until recently. But periscope cameras take a different approach. The sensor can still be oriented the same way it normally would, but prisms direct the light from the lens along the body of the phone, giving much more leeway for optical design.

This is not at all a new concept. Oppo showed its work on the technique in 2017, and Huawei's P30 Pro in 2019 was the first phone to ship with a periscope camera. Its 5x telephoto lens was a genuine breakthrough for mobile photography. Oppo followed up the same year with its own commercial version, the confusingly named but still very good “Reno 10x Zoom”.

Since then, 5x telephoto cameras have been common on flagship Android phones from brands like Vivo and Realme, while Huawei and Samsung have pushed boundaries with 10x modules. These cameras tend to have familiar tradeoffs — the optical quality and light-gathering ability isn't what you'd expect from the phone's primary camera, but they do allow for much greater reach and versatility.

For example, here's a shot from the Xiaomi 13 Ultra's ultrawide lens:

And here's one from its 5x periscope telephoto, shot from the same seat and aiming at the far corner of the pitch:

That's what iPhone users have been missing out on these past few years since periscope cameras took off in the Android world. The biggest question is how Apple is going to implement its own take on the tech.

It's a little surprising to me that Kuo and Gurman haven’t given a specific figure for the periscope camera’s magnification. The focal length should be apparent from the supply chain, though you'd need to know the final size of the sensor as well to calculate the actual field of view. We are talking about fractions of millimetres here, so any slight change could also have an effect on telephoto magnification.

5x telephoto cameras are by far the most common type of periscope lens in Android phones these days. Almost every brand has shipped one. They do, however, have their issues, and I don't think they're what Apple is going to use.

The iPhone 14 Pro Max has a 3x telephoto lens. Swapping that out for a 5x lens would degrade image quality between 3x to 4.9x magnification, which I would think is a more typically useful range for most smartphone snaps than 5x and beyond. Other companies like Xiaomi get around this by going with a four-lens array that includes a conventional 2x or 3x telephoto, but all indications are that Apple is sticking with three.

Another problem with 5x periscope cameras is their low-light ability. Even using the extra space afforded by the periscope technique, these cameras tend to use smaller sensors and apertures than other modules. The Xiaomi 13 Ultra's periscope lens is f/3, for example, and that's one of the better ones. It's tough to use slower shutter speeds with longer focal lengths, because hand movement is exaggerated, so noise is often cranked up in low light.

The Xiaomi 13 Ultra, with its 5x periscope lens at the bottom.

I don't think it'd make sense for Apple to put a 5x periscope telephoto in a three-camera system. The quality would be worse than the (already not great) 3x lens on the 14 Pro, and the focal length would be less versatile.

There is another approach that would be a better fit for the iPhone. Oppo's excellent Find X6 Pro, which I reviewed earlier this year, has a periscope telephoto that only offers 2.8x magnification over the primary one-inch sensor. The reason for this is that it allows Oppo to use a larger sensor and faster lens than its 5x competitors.

The Find X6 Pro's periscope camera has an f/2.6 aperture and a comparatively huge 1/1.56" sensor, which is much bigger than you'd find on any phone's conventional 3x module. For comparison, the iPhone 14 Pro's 3x lens is paired with a tiny 1/3.5" sensor and a slightly slower f/2.8 aperture. All things being equal, bigger sensors get you better image quality because they can capture more light.

Oppo's 2.8x camera is good enough that you can get credible 5.6x-equivalent shots by cropping into the middle of the sensor; that's also a technique Apple introduced last year for 2x shots on the iPhone 14. I suspect that's what Apple is going to do with the 15 Pro Max's telephoto lens: it'll claim "optical quality" 6x zoom (or thereabouts) from a lens that actually has a much shorter focal length. That way, the phone will be able to take solid pictures at 0.5x, 1x, 2x, 3x, and 6x, plus however far Apple wants to push its digital zoom algorithm beyond that.

The Find X6 Pro has the best all-around zoom lens on a phone, in my estimation, and I think the approach would be a great fit for Apple. Here's a photo I took at 5.6x at a concert last week:

You can tell it’s a little sharpened, but it’s a heck of an improvement over what I was able to get out of my iPhone 14 Pro Max from the same spot:

That’s what to watch out for at Apple’s event today. See how they talk about 3x zoom, how they explain the 6x capability, and especially whether they give any details on the camera’s sensor size.

Or hey, I could be completely wrong about all of this. Maybe it really is just a 5x or 6x lens, and maybe the sensor will be small. I am convinced, though, that Oppo has the best approach to a three-camera system on the market right now, and I’ll be disappointed if Apple doesn’t go the same route — or come up with something even better.