Smartphone cameras explained 2

Good day everyone, we started recently a discourse on the entire smartphone camera infrastructure. I have titled this talk Smartphone cameras explained 2.

We have already listed the parts of a camera as well as the other parts of the phone that function in image production.

Read: Introduction to Smartphone cameras 1

Image Sensors

Today, I want to talk about image sensors. This is one very key ingredient of the whole photography equation.

Unfortunately it is also overlooked a lot of the time.

An image sensor is an electronic plate or surface that sits at the back of the camera.

It’s main job is to catch light and convert the light energy into digital form (pictures).

Introduction to Smartphone cameras

An image sensor

In the above image, you can see what a typical sensor looks like.

This is what captures the object that you’re trying to snap. From a human face to flower to a building etc.

Above you can see that I have labelled it with 1 and 2.

The number 1 part refers to the size of the sensor. (I’m going to explain it soon.)

The number 2 part is the inside of the sensor and contains the pixels (also known as picture elements).

Read: How to read smartphone camera specifications

Sensor Size

The sensor size refers to the physical size of the image sensor, that is how big it is.

It is measured in fractions of an inch e.g 1/2″. The (“) sign means inches.

Just like with the aperture, the smaller the number, the bigger the size.

So if we have two cameras. Camera A has a sensor size of 1/2” and camera B has a sensor size of 1/3.5″…

Camera A has the bigger sensor.

If the message about sensor size is clear, we’ll move along to number 2.

What are Smartphone image sensors and how do they work?


The number 2 area is the inside of the sensor and it contains what are known as pixels.

The pixels (or picture elements) are the areas of the sensor that catches the light.

Two things that you need to keep in mind here are;

The number of pixels
The size of the pixels

Number of pixels (Pixel count)

The number of the pixels refers to how many pixels are physically present on the sensor.

If a sensor has only one pixel, it will be called a 1 pixel camera or a 1 p camera.

If a sensor has 1,000,000 pixels then it will be known as a 1 mega pixel camera.

1,000,000 pixels = 1 mega pixel (1MP)
10,000,000 pixels = 10 mega pixels (10MP)
12,000,000 pixels = 12 mega pixel (12MP)
48,000,000 pixels = 48 mega pixel (48MP)

This is the part of the camera that a lot of people know. The Mega pixel count or the number of mega pixels.

This is the part that companies advertise to us as well.

Read: Megapixels vs Sensor/Pixel size

Pixel size

The second part that we need to look at that is even more important is the pixel size. That is the part that they don’t advertise to us.

Think of pixels like buckets.

If you want to capture and store rainwater. Which size of bucket would you prefer? A very small bucket or a big bucket or basin if possible?

Obviously, the best option is to use a big bucket. That way you can catch more water.

The same thing applies here.

If you have small pixels and big pixels, the big pixels will catch light better than the small pixels.

The more light a sensor can catch, the better the picture will look.

Pixels are measured in microns which are written as μm.

In this system, there’s no inverse rating. The numbers are as you see them.

So if you have two cameras. Let’s say camera A has pixel sizes of 0.8μm and camera B has pixel sizes of 2.0μm.

Then camera B has the bigger pixels.

In order to avoid information overload. I’ll stop today’s talk here and do a quick recap.


A sensor is the part of the camera that captures the images. It captures light and turns it into pictures.

The sensor has 3 important metrics to look at.

1. Sensor size
2. Number of pixels
3. Pixel size

Sensor size is inversely measured meaning that the smaller the number the bigger the size.

The number of pixels is rated in units known as megapixels. These are 12mp, 16mp, 32mp, 48mp, 50mp, 64mp, 108mp, 200mp etc.

The last one is the pixel size.

This one is measured in microns and written as μm.

For many of us, I’m sure this is a revision class, but if this is new to you.

You may need to read it more than once, depending on the speed of your assimilation.

I’ll be calling it an evening and I’ll be around to field any questions you may have.

Good evening.

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