iPhone 14 pixels: Why the 48MP sensor is not the big camera news this year

Let’s talk pixels. Specifically, iPhone 14 pixels. More specifically iPhone 14 Pro pixels. Because although the main news is that the latest Pro models offer a 48MP sensor instead of a 12MP, it’s not actually the most important improvement Apple has made to this year’s camera.

Actually off four biggest changes this year, the 48MP sensor is for me the least important. But bear with me here, as there’s a lot we need to unpack before I can explain why I think the 48 MP sensor is far less important than:

  • The sensor size
  • Pixel binning
  • The photonic engine

One 48 MP sensor, two 12 MP sensors

In everyday speech, we talk about the iPhone camera in the singular and then refer to three different lenses: main, wide-angle and telephoto. We do this because it’s familiar – that’s how DLSRs and mirrorless cameras work, one sensor, multiple (interchangeable) lenses – and because it’s the illusion Apple creates in the Camera app, for convenience.

The reality is of course different. The iPhone actually has three cameras modules. Each camera module is separate and each has its own sensor. When you press e.g. 3x button, you don’t just select the telephoto lens, you switch to another sensor. When you slide-zoom, the camera app automatically and invisibly selects the appropriate camera module, and thereafter makes any necessary pruning.

Only the main camera module has a 48MP sensor; the other two modules still have 12MP.

Apple was very upfront about this when they introduced the new models, but it’s an important detail that some may have missed (our emphasis):

For the first time ever, the Pro series has a new 48 MP main camera with a quad-pixel sensor that adapts to the image being captured and features second-generation sensor-switching optical image stabilization.

The 48 MP sensor works part-time

Even when using the main camera, with its 48MP sensor, you’ll still only capture 12MP photos by default. Again, Apple:

For most images, the quad-pixel sensor combines every fourth pixel into one large quad-pixel.

The only time you shoot in 48 megapixels is when:

  • You are using the main camera (not telephoto or wide-angle)
  • You shoot in ProRAW (which is off by default)
  • You are shooting in decent light

If you want to do this, you can see here how. But for the most part, you won’t…

Apple’s approach makes sense

You might ask, why give us a 48MP sensor and then mostly not use it?

Apple’s approach makes sense because, in truth, there is much few times when shooting in 48MP is better than shooting in 12MP. And since it creates much larger files, and takes up your storage with a voracious appetite, it makes no sense to have this as the default.

I can only think of two scenarios where taking a 48 MP image is useful:

  1. You intend to print the image in large size
  2. You need to crop the image very heavily

The second reason is also a bit questionable, because if you need to crop that much, you might be better off using the 3x camera.

Now let’s talk about sensor size

When comparing any smartphone camera to a high quality DSLR or mirrorless camera, there are two major differences.

One of them is the quality of the lenses. Standalone cameras can have much better lenses, both because of physical size and because of cost. It is not unusual for a professional or keen amateur photographer to spend a four-figure sum on a single lens. Of course, smartphone cameras can’t compete with that.

The second is sensor size. All other things being equal, the larger the sensor, the better the image quality. Smartphones, by virtue of their size and all the other technology they need to fit in, have much smaller sensors than standalone cameras. (They also have limited depth, which imposes another significant limitation on sensor size, but we don’t need to get into that.)

A sensor the size of a smartphone limits image quality and also makes it harder to achieve shallow depth of field – so the iPhone does this artificially with Portrait mode and Cinematic video.

Apple’s large sensor + limited megapixel approach

While there are obvious and less obvious limits to the sensor size you can use in a smartphone, Apple has historically used larger sensors than other smartphone brands — which is part of the reason the iPhone was long seen as the phone of choice for camera quality. (Samsung later switched to doing this as well.)

But there is another reason. If you want the best possible image quality from a smartphone, you want it too pixels to be as large as possible.

This is why Apple has stuck religiously to 12 MP, while brands like Samsung have crammed as much as 108 MP into the same size sensor. Squeezing many pixels into a small sensor increases noise significantly, which is especially noticeable in low-light images.

Ok, it took me a while to get there, but I can now finally say why I think the bigger sensor, pixel binning and the photonic engine is a far bigger deal than the 48 MP sensor…

#1: iPhone 14 Pro/Max sensor is 65% larger

This year, the main camera sensor in the iPhone 14 Pro/Max is 65% larger than that of last year’s model. Of course, that’s still nothing compared to a standalone camera, but for a smartphone camera, it’s (pun intended) huge!

But as we mentioned above, if Apple squeezed four times as many pixels into a sensor that’s only 65% ​​larger, it would actually produce worse quality! This is exactly why you still mostly shoot 12MP photos. And it’s thanks to…

#2: Pixel binning

To capture 12 MP images on the main camera, Apple uses a pixel binning technique. This means that data from four pixels is converted to one virtual pixel (average of the values), so the 48MP sensor is mostly used as a larger 12MP.

This illustration is simplified, but it gives the basic idea:

iPhone 14 pixels: Pixel binning illustration

What does it mean? Pixel size is measured in microns (one millionth of a meter). Most premium Android smartphones have pixels that measure somewhere in the 1.1 to 1.8 micron range. When the iPhone 14 Pro/Max uses the sensor in 12MP mode, it effectively has pixels measuring 2.44 microns. It is a really significant improvement.

Without pixel binning, the 48MP sensor would – most of the time – be a downgrade.

#3: Photonic engine

We know that smartphone cameras obviously can’t compete with standalone cameras in terms of optics and physics, but where they can compete is in computer photography.

Computational photography has been used in SLRs for literally decades. For example, when you change measurement mode, it instructs the computer inside your DLR to interpret the raw data from the sensor in a different way. Similarly, in consumer DSLRs and all mirrorless cameras, you can choose from a number of photo modes, which in turn tell the microprocessor how to adjust the data from the sensor to achieve the desired result.

So computational photography already plays a much bigger role in standalone cameras than many realize. And Apple is very, very good at computer photography. (Ok, it’s not good for cinematic video yet, but give it a few years…)

The Photonic Engine is the dedicated chip that powers Apple’s Deep Fusion approach to computational photography, and I can already see a huge difference in dynamic range in images. (Examples will follow in an iPhone 14 diary next week.) Not just the range itself, but in the intelligent decisions being made about Which one shadow to bring out, and Which one highlight to tame.

The result is significantly better images, which has as much to do with the software as the hardware.

Closing

A dramatically larger sensor (in smartphone terms) is a really big deal when it comes to image quality.

Pixel binning means that Apple has effectively created a much larger 12MP sensor for most images, allowing the benefits of the larger sensor to be realised.

Photonic Engine means a dedicated chip for image processing. I can already see the benefits of this in real life.

More to follow in an iPhone 14 Diary when I put the camera to a more extensive test over the next few days.

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William

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