A camera is a magical device that can capture the most beautiful moments of our lives. But have you ever wondered how a camera freezes the moment with a single click? Well, the core part of a camera is the sensor that sees the world and captures the details of the scene. But how does the sensor do that? How does it work? In this article, we are going to discuss this very topic. So let’s get started.
The image processors mimic the functionality of our biological eye for capturing what stands in front of it. So to understand how a sensor works, we first understand how our eyes work. When light enters into our eyes from different objects, it falls on the retina. The retina is connected to photoreceptors that convert the light into an electrical signal and then transfer it to our brain. Our brain then decodes the signal and creates the sensation of an actual image. That’s how our eyes work.
The same principle is followed in a camera image sensor, but electronically. There are two types of sensors that are commonly used these days. One is the charge-coupled device or CCD, and the other one is the complementary metal-oxide-semiconductor or CMOS in short. Both the sensors are made of millions of photosites or in simple terms, Pixels.
When you press the shutter button of a CCD camera, the sensor is exposed to light. The light captured by the pixels instantly converts into electric charges. Then there is a horizontal shift register and vertical shift register, which moves each of the electric charges collected by each pixel into the voltage converter and converts it into voltage. Then the voltage is amplified using an amplifier. After being amplified each voltage is then sent to the analog to digital converter for being converted into a digital signal. And then, it is sent to the processor for further analysis. So the button line is, each signal is processed individually, one by one. So it takes a little time to finish all the tasks. Moreover, it will also increase your battery consumption to a significant level. On top of that, it is expensive. If you wonder why! Then it is because this sensor is capable of capturing low-noise images as each electric signal passes through rigorous filtering. So it is used in sophisticated projects where quality is an absolute need like capturing space images or aerial images for commercial purposes.
Now let’s talk about the most popular image sensor of our time, the CMOS sensor. It is all the same as the CCD sensor, except there is an additional circuit associated with each pixel that converts the light of the respective pixel. So this process makes the horizontal and vertical shift process redundant. And the wait for each signal to be processed and amplified individually is no more necessary in the CMOS sensor. So clearly, CMOS sensors can significantly increase the speed of sensor readout while using a lesser amount of power. Moreover, it is less expensive than the CCD sensor, making it perfect for consumer-grade cameras. However, CMOS sensors are more affected by noise and cannot perform much effectively in low-light situations.
So that was all about how the sensor works in cameras. Hope now you have a comprehensive idea of the functionality of lenses in cameras. But camera sensors are getting better day by day and new technologies are coming with time.