Sensor on second iPhone 7 Plus camera is smaller than main one, calculations show

Apple hasn’t revealed the sizes of the camera sensors used in the iPhone 7 and 7 Plus, but a Reddit user has used EXIF data from the Sports Illustrated photos to calculate them. They seemingly reveal that the main sensor is exactly the same size as the one in the iPhone 6s, while the sensor for the 2x telephoto lens is somewhat smaller …

Using the EXIF data from the teaser photos courtesy of Sports Illustrator, we can calculate the sizes of both sensors (some of their photos were taken with the telephoto lens). Apple claims a 28mm (in 35mm equivalent) wide angle lens for the main sensor, and 56mm lens for the telephoto (35mm equivalent calculation, again).

The actual focal length of the main camera is 3.99mm, derived from one of the photos EXIF data. A 1/3in sensor has a crop factor of 7.21, and the iPhone 6S’ sensor is 1/3in. The math is below:

iPhone 6S (1/3in sensor) = 4.15mm x 7.21 = 29.92mm for a 35mm equivalent lens.

iPhone 7 Plus main sensor = 3.99mm x (7.21?) = 28.7679mm, very close to Apple’s claimed 28mm.

iPhone 7 Plus telephoto sensor = 6.6mm x (8.6?) = 56.8mm, very close to the claimed 56mm as well. For a 1/3.6in sensor, the crop factor is 8.6.

Smaller sensors for the same number of pixels tends to mean more ‘noise’ in the photo (visible artefacts that degrade the photo quality). However, Apple has a good track-record at noise-reduction.

We saw this when I tested the iPhone 6s camera. What we saw then was Apple moving from 8MP to 12MP in the same sensor size, which should have meant significantly more noise. Apple instead applied aggressive noise-reduction. The result is a photo which looks just as good at normal viewing sizes and distances, but a loss of sharpness when you look closely at a small crop from the photo (seen below).

The impact here should be less significant, and I’d again only expect to see it when pixel-peeping, but it does illustrate one of the compromises Apple had to make to fit in the second camera, which adds weight to the idea that the dual-camera system isn’t likely to make it into a 4.7-inch iPhone anytime soon.