Why iPhone and Smartphone Cameras Still Lag Behind DSLRs

It's the same thing every year. Apple, Google, and Samsung launch their flagship phones, and people go wild over the cameras. Soon enough, we hear someone saying the death of the DSLR camera is near. But are these smartphones really catching up to DSLRs? What makes a DSLR better?

It takes only one look at a comparison in output to know that phones aren't yet good enough. And it makes sense once you find out what are the important specs in any digital camera.

Sensor Size Does Matter

The biggest difference between a DSLR camera and a smartphone is the sensor size. And that alone is enough to create that chasm. Till phones have sensors that match those of DSLRs, it's silly to think the output will be as good.

The sensor is the base technology of how a camera works. Its job is to capture all the light coming in through the lens. The larger the size of the sensor, the more light it can capture. The more light a sensor can capture, the more detailed and true your photos look.

Typically, a DSLR camera's sensor will be one of the following:

Full Frame: 36 x 24 mm
APS-C: 23.6 x 15.6 mm
1.5-inch: 18.7 x 14 mm
Mirrorless cameras have 4/3-inch (17.3 x 13 mm) sensors
Top point-and-shoot cameras (e.g. Sony RX100 II) feature 1-inch sensors

Want to take a guess at the sensor size of smartphone cameras? The Google Pixel 2, arguably the best smartphone camera today, has a sensor measuring 1/2.6 inches (5.5 x 4.1 mm).

So a DSLR's sensor is anywhere between 4-6 times larger than a smartphone's sensor.

Stop Counting Megapixels

Even if the camera's sensor size is larger, its megapixel count might not be as high. The Nokia 808 PureView famously had a 41-megapixel camera, but the sensor size was only 1/1.2 inches.

But its pictures pale in comparison to the Canon EOS 1300D or Nokia D3400. Both these DSLR cameras have APS-C sensors at only 24 megapixels. So how do they have better pictures even with megapixels?

Well, you shouldn't believe in the myth of megapixels. Marketers push this statistic because it is a number that can be manipulated easily. The truth is, cramming more megapixels onto a sensor alters the image quality.

In fact, less pixels on a larger sensor result in larger pixels, which in turn capture more light. And this means the image processor will reduce noise.

The Unsung Hero: Image Processor

The sensor's job is to capture light and turn all the colors into electronic signals. But the result is something akin to a jigsaw puzzle of different color signals. The image processor is the unsung hero who takes those colors and builds an image out of them.

This image processor is the "brain" of the camera. It has to read the light meter, access and understand colors available in the sensor, check the time of capture, and smartly put together the puzzle. The accuracy of what you see with what photo you get is as much the function of the processor as any other part.

This is a tough job for any image processor. And this is why you sometimes see "noise" in photos. "Noise" is a wrongly placed pixel of color in finishing the jigsaw puzzle. The image processor also has more important jobs (like the Bayer transformation for speed) but those are too technical to get into here.

Now think about it this way. A DSLR has an image processor whose job is to understand photography and nothing else. It's a dedicated worker whose entire life is about putting together accurate images.

Meanwhile, smartphones also have image processors, but these work along with a whole lot of other circuitry. And they have limited space to work on the limited size of a phone. It's no surprise that a dedicated DSLR image processor does a better job than smartphones.

Aperture, Shutter Speed, Lenses, and More

Apart from the sensor size and the image processor, smartphones still haven't caught up in other aspects. The lenses, for example, are still primitive compared to DSLRs. Of course, you can change lenses and you get much more control on DSLRs. But apart from that you only get wide-angle lenses on phones. (This is mainly because a wide-angle lens will increase the sensor size in that limited space.)

Smartphones have done better with aperture and shutter speed, the basics of a camera. The new lot of iPhones and Pixels manages f/1.8 aperture, which is comparable to mirrorless and DSLR cameras.

Apart from lenses though, you can expect smartphones to make rapid progress over the next few years. There aren't major long-term physical restricting the introduction of better camera technology on phones. It will just take time.