Apple used 'tetraprisms' to cram a 120mm lens into the iPhone 15 Pro Max

One of the main benefits of Apple's "pro" iPhones is the camera rig, which somehow gets pretty significant improvements every year. The iPhone 15 Pro and 15 Pro Max are no exception. Revealed on Tuesday at Apple's annual fall event, both phones sport three-lens arrays, but there are a handful of noteworthy details this year, particularly for the iPhone 15 Pro Max.

For the first time, the iPhone 15 Pro Max has a "5X" optical zoom, with a 120mm focal length equivalent. That's significantly longer than the 3X 77mm focal length that you find on the standard iPhone 15 Pro (as well as both of last year's 14 Pro phones). It has a 25 percent larger sensor than the 3X camera in the 14 Pro Max while keeping an f/2.8 aperture, which Apple says is the largest of any smartphone in this optical range.

Usually, longer telephoto lenses are literally longer in physical space, as well. To get around this, Apple is using what it calls a "tetraprism" design. Light rays are reflected four times through the glass which lets the light travel for longer without needing a physically larger design. There's a more advanced image stabilization system on board as well, something necessary when shooting at longer focal lengths. Of course, we're going to want to try this camera out to see how it performs, but it sounds like an impressive upgrade for anyone buying the iPhone 15 Pro Max — if you're an avid smartphone photographer, these changes alone might make the Max worth buying over the smaller model.

A number of other updates are coming to both Pro-level iPhones. The "main" camera is 48 megapixels again, but advances in using that resolution will allow you to shoot with that main lens at your choice of three effective focal lengths: 24mm, 28mm and 35mm. You can choose your preferred setting and set it as your default. You won't typically output photos at the full 48-megapixel resolution — Apple combines pixels to improve low-light performances and the default output will be 24 megapixels. But if you'd rather use the full resolution, you can shoot in 48-megapixel ProRAW format, or in HEIF for a file that's smaller and more easily shareable.

As with last year's cameras, the "main" shooter can also use the center of that 48-megapixel sensor to give you effective 2X zoom photos at 12 megapixels. And the smaller iPhone 13 Pro retains the 3X optical lens.

Naturally, there are software improvements all throughout the iPhone's photo processing system, which Apple calls the Photonic Engine. That includes things like better low-light performance, improved HDR, continuous zoom when shooting portraits, the ability adjust portrait focus after the photo has been shot, improved dynamic range and more. But one of the ones that'll be immediately obvious is the iPhone automatically switches into Portrait mode when focusing on a human or pet, saving you the step of having to decide to activate it.

While most of the camera improvements this year focused on photos, there is a big video change directly tied to a future Apple device. Later this year, the iPhone 15 Pro lineup will be able to shoot spatial video that can be viewed on the upcoming Vision Pro headset. These are essentially 3D videos shot using both the ultra-wide and main camera sensors to give a more immersive experience when using Apple's headset. Obviously, very few of us have had the chance to see how this works, but it's a smart way for Apple to get people shooting videos that'll presumably look compelling on the Vision Pro.

While the standard iPhone 15 received a more modest set of upgrades, there's still a few things worth noting. The main camera sensor has been upgraded to 48 megapixels. This means that you can get a 2X zoom on the standard iPhone 15 for the first time, as it can crop into the center of the sensor and produce a 12-megapixel image without the degradation you get from digital zoom. You'll also get 24-megapixel images that combine pixels to improve low light and detail while still offering manageable file sizes. These are good improvements for people who don't want to think too much about the finer points of iPhone photography — but if you want more control over your images, the Pro models remain the best choice.

The iPhone 15 Pro Max will be available for pre-order on September 15 for $1,199 and will ship on September 22. In the meantime, check out some early impressions from Engadget's Deputy Reviews Editor, Cherlynn Low, who was on the ground in Cupertino covering the event.

Update, September 20 2023, 2:27PM ET: Read our full review of the iPhone 15 Pro and 15 Pro Max, which is now live on Engadget.