When it comes to smartphone photography, are more megapixels always the answer?

If you're into smartphone photography, one of the specifications you're probably checking out is a smartphone camera's megapixel count. But is it really a reliable indication of image quality?

If you look at SLRs and mirrorless cameras and compare them against smartphones, you'll find that some entry-level and mid-range phones have higher pixel counts. But they still have worse image quality when compared.

So, let's look and see which is more important: the pixel count or the sensor size.

Before diving into the topic, we must first figure out what camera sensors are and how they work. A digital camera must convert light into electrical signals when taking a picture. To do so, it uses the lens to focus the light onto an image sensor.

However, the image sensor isn't just one single light sensor. Instead, it's made of many smaller light sensors called pixels. Each pixel measures how much light it gets and converts it into a signal. The camera's onboard computer then captures the signal from each pixel and constructs an image out of them.

There's more to it than what's written above, but that's the gist of how digital cameras make photos. If you want to know more, you can check out our primer on how imaging sensors work.

Given that individual pixels capture light, many will argue that megapixels matter. And that's true to a point. After all, an image's print size will depend on its number of pixels. For example, at the ideal 300 pixels per inch resolution, you can only print an 8 x 10-inch image from an 8 MP photo before it starts to blur.

However, in this day and age, where most of our photos are typically stored and shared on our phones, having a 64 MP camera on a smartphone is excessive. The flagship mirrorless and SLR cameras from Canon only have 24 and 20 megapixels, respectively. Even professional medium-format cameras from Hasselblad only sport 50 megapixels.

You must remember that pixels must live inside a sensor. So, if you're cramming 108 million pixels in a 1/1.33" sensor, those pixels must be exceptionally tiny. When you reduce the size of your pixels, you also reduce the amount of light it captures. This reduction will have an impact on the final result of your image. Here are its possible effects:

This section will discuss a lot of camera jargon. If you're unfamiliar with them, you should read this list of photography terms every photographer should know.

When you reduce the amount of light a given pixel captures, it increases that individual pixel's signal-to-noise ratio. That's because there will always be noise, and you can only overcome it by filling the sensor with actual light signals. But if your camera uses small pixels (by packing in as many pixels as possible in a small sensor package), there will not be as much light data to overpower the noise already there.

When you're shooting in dark areas, a camera with a smaller sensor will be at a disadvantage. Smaller sensors will capture less light for a given exposure time. So, to ensure that it can capture what you're seeing, the camera will either use more power to increase its ISO (thus increasing noise) or lower the shutter speed to gather more light (which means you must have a tripod or very steady hands).

Smaller sensors usually have deep depths of field. That's because a smaller sensor will also capture a smaller area. So, if you want to photograph a flower, you'll have to step further back to capture it in its entirety.

However, a camera with a larger sensor captures a bigger area. So, if you want to fill your camera's frame with the flower, you'll have to either go closer to the flower or use a lens with a longer focal length. When you do so, you get a shallower depth of field in your image, thus making your subject pop out of the background.

When you have a smaller sensor, you also get a lesser angle of view. So, if you want to capture a wide scene but have a smaller sensor, you'll have to use a wider lens. However, a wider lens can introduce distortion, like the fish-eye effect.

Perhaps the only advantage of a smaller camera sensor over a larger one is in price and size. Since smaller sensors consume less energy and need fewer resources to produce, they're generally more affordable compared to larger image sensors.

Furthermore, smaller sensors are physically smaller than their larger counterparts, allowing them to be placed in thinner devices, like smartphones, without needing massive camera bumps. They also need smaller diameter lenses, so you don't need massive holes at the back of your phone if you have a smaller sensor.

Despite the disadvantages, smartphone makers still strive to add as many pixels as possible to their cameras. But besides sounding impressive on paper, smartphone companies are keen on adding more pixels to their smartphones to take advantage of computational photography.

Smartphones can overcome many of these limitations by using powerful chips and AI. That's why phones today have excellent imaging performance, even if they have small camera sensors.

For example, the Google Pixel 6 and the Apple iPhone 13 Pro Max can produce some of the best images today. Their output is generally clean and free from noise; even their night shots are sharp and crisp. And although the artificial bokeh in these devices isn't as good as the real thing, they're getting better with every generation.

Still, you'll find that the trend in smartphone cameras is larger sensor sizes. You'll notice this in the iPhone—the iPhone 11 Pro Max has a 1.4µm pixel size, while the iPhone 12 Pro Max sports a sensor with 1.7µm pixels. The iPhone 13 Pro Max has an even larger 1.9µm pixel size, which makes it arguably one of the best camera phones today.

Many phone makers use pixel counts to wow potential buyers. However, they're really not a great indication of quality. After all, you can find entry-level smartphones with 48 MP rear cameras that produce terrible images.

Many manufacturers add numbers and other jargon to sound cool or advanced, so it's best that you know which specifications to look at and which to disregard. But if you're buying a smartphone for its image quality, the best thing you can do is to look at reviews and actual image samples before making a choice.

Jowi is a writer, a career coach, and a pilot. He's been using, discovering, and exploring PCs since Windows 95 and was on board the Android bandwagon since Gingerbread. He started occasionally writing in 2015 and transitioned to it full-time in 2020. Jowi finished a university degree with related units in journalism in 2012. But even before he stepped into university, he's been known by his friends and family as the go-to person when anything computer-related requires explanation.

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