iPhone 15: Apple Shares Rationale Behind Camera Features and Limitations

Apple's new iPhone 15 series includes several new camera features, but not all of them will be visible to casual photographers, and Apple says it is relying on third-party developers to make these extra controls accessible to enthusiasts and filmmakers.

In an interview with PetaPixel, Jon McCormack, Apple's vice president of camera software engineering, explained the company's rationale behind this middle-ground approach, while also shedding light on some of the decisions it took when finalizing the ‌iPhone 15‌ feature set.
"It really is, in my mind, all about allowing people to go chase their vision and this goes from the harried parent of a toddler where their vision is, 'can I get my kid in frame as they take their first step' all the way through to a pro or a creative who has got a very specific artistic vision in mind and want to get there as quickly as possible," said McCormack.

"Behind the big red button… the thing you're worrying about is the frame and the moment because honestly, that's the most inspiring part of any photograph or any video."

iPhone 15 Pro Focal Lengths

iPhone 15 Pro users can choose from 24mm, 28mm, and 35mm focal lengths when taking photos, simply by tapping the 1x button in the Camera app. However, for technical reasons, these focal length options aren't available when shooting video, and the Camera offers a zoom ring instead.

"When you're shooting [photos], we gather a bunch of data to let you keep shooting and then sort of keep processing in the background, so we have more time and this is just something we can't do in video," McCormack told PetaPixel.

Log Video Encoding

When encoding video in log mode, the camera uses a logarithmic curve to more efficiently compress the colors in such a way as to offer a wider dynamic range. This allows filmmakers to maximize dynamic range as much as possible without overexposing, or push the shadows as much as possible to minimize noise.

"We go for a middle-ground exposure," said McCormack. "When you go into log, there's no tone mapping so you can have much more precise control over what your exposure is."

However, while the iPhone can now shoot in ProRes Log, there are no on-screen controls or waveform in the native Camera app to control exposure. Instead, Apple is relying on third-party app developers to bring these controls to power users, which serves to keep the standard Camera interface uncluttered. Apple said it will also be providing LUT profiles to editors on September 22.

External Video Transfer via USB-C

The ‌iPhone 15 Pro‌ and Pro Max support USB3 transfer speeds from the new USB-C port, but only ProRes files recorded in 4K at 60p can be recorded to an externally attached SSD. All other video and phot modes must be saved to the ‌iPhone‌ first and transferred later. Apple told PetaPixel this was an in-house design decision focused on supporting ProRes workflows.

24 vs 48 Megapixels

Last year, Apple limited the default camera settings to 12MP, but this year it is limited to 24MP, despite the main camera's sensor's 48MP capabilities. The reason for this, McCormack explained, is that there is slightly more dynamic range when shooting in 24MP.
"When shooting at 24-megapixels, we shoot 12 high and 12 low — we actually shoot multiple of those — and we pick and then merge. There is, basically, a bigger bracket between the 12 high and the 12 low. Then, the 48 is an 'extended dynamic range,' versus 'high dynamic range,' which basically just limits the amount of processing. Because just in the little bit of processing time available [in the 24 megapixel] we can get a bit more dynamic range into Deep Fusion. So what you end up with in the 24, it's a bit of a 'Goldilocks moment' in that you get all of the extra dynamic range that comes from the 12 and the detail transfer that comes in from the 48."
McCormack also said there's zero shutter lag when shooting at 24-megapixels, whereas shooting at full 48-megapixel resolution doesn't provide an instantaneous shutter.

Keeping Photography Approachable

Ultimately, Apple's goal is to ensure that ‌iPhone‌ photography remains approachable, according to Maxime Veron, senior director of ‌iPhone‌ product marketing. "For the vast majority of our customers, we just aim to process everything in the background so that the process is invisible and out of the way so that people can take great photos and videos and capture beautiful, true-to-life moments in one click," she told PetaPixel.

Veron added that at the same time, Apple wants to meet the ever-growing demands of its enthusiast customers, allowing them to use the same hardware to capture images that can grace the cover of a magazine.

The full interview can be found at PetaPixel. All of Apple's new ‌iPhone 15‌ models are now available to order and launch this Friday.
Related Roundups: iPhone 15, iPhone 15 Pro
Related Forum: iPhone

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