The iPhone 7 Plus uses its second camera less often than you think

One of the biggest features on the brand new iPhone 7 Plus is the implementation of its dual camera system where one camera was your bog standard wide-angle smartphone shooter, while the other featured a short telephoto to give the smartphone 2x optical zoom, versus the digital zoom found on most smartphones.

One would think that by simply hitting the 2x zoom button, you would be utilising the telephoto lens. However, an interesting discovery by Glenn Fleishman over at Macworld reveals that the handset uses digital zoom more often than you think even at 2x.

For those who are unfamiliar with cameras, here’s a quick crash course on why optical zoom is almost always better than digital zoom. When you use digital zoom, the camera software essentially “zooms in” on the image by cropping your full-sized photo into that particular spot and blows it up. This means that you’re not utilising your entire camera’s sensor, rather just a portion of it.

A rather rudimentary explanation, but I think you get the general idea behind digital zoom. So, if you use digital zoom, you will almost always end up with a worse picture than the one that your smartphone is capable of capturing.

With optical zoom, on the other hand, zooming is no longer done with the software inside your camera. Instead, it is the lens element that directs the light into your camera sensor that does the zooming. This means that you will still be getting your camera’s full image quality when you zoom in.

Lesson over.

So, now that you understand why optical zoom is so important, you would also probably understand why everyone got so excited when Apple announced that the iPhone 7 Plus would be able to do this with its dual camera setup.

The iPhone 7 Plus does this by having two different lenses: The first is a wide angle 4mm lens in front of the camera, giving it an equivalent focal length of 28mm (not ultra wide but quite wide); while the second sensor has a longer 6.6mm lens, giving it an equivalent focal length of 56mm (so short telephoto, not super zoom).

In the iPhone 7 Plus’ world, Apple uses their camera software to swap between these two lenses depending on how much zoom their users want. However, since it’s two separate lenses (one is 2x from the other) Apple also has to fill in the gaps between the two lenses with digital zoom.

By that logic, it would make sense for you to think that as long as the camera is zoomed in by 2x or more, the iPhone 7 would always be using the telephoto lens to capture images. I thought so too until I read Macworld’s comprehensive article about why I had the wrong idea.

Based on that article, the author identified — after intensive testing — that the choice of using either digital zoom or switching to the other lens is dependent on two factors:

1. The lighting conditions.
2. How close you are to the subject.

Lighting condition is a factor simply because the primary 4mm camera captures better light information and light detail. This is in part thanks to its faster f/1.8 aperture lens which lets in more light than the f/2.8 telephoto lens. The wide lens also handles low light better because of its optical image stabilisation which allows it to use a lower shutter speed (which lets in more light) without making the image blurry from shaky hands.

So, if you go to 2x zoom on your subject in low light where you need a slow shutter speed, the iPhone 7 Plus will always use the 4mm lens and digital zoom. In good lighting, both lenses will work together with the 6.6mm shooter capturing detail while luminosity is derived from the 4mm camera.

For the second factor, distance is an issue because the telephoto lens can’t focus within a foot of the subject, while the 4mm lens can. So, Macworld suggests that instead of standing a little further and tapping the 2x zoom button for macros, you should just walk closer to the subject.

If you want a more detailed breakdown and explanation of this phenomenon, definitely check out Macworld’s article. The author also lists a bunch of tips and tricks to get the most out of your photos with the iPhone 7 Plus.

In the meantime, what do you guys think of this information? Let me know in the comments below.

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