Digital camera - Sensor
Sensor of the digital camera
In the next few lessons we are going to discuss:
- The sensor consists of…
- RGB
- Processing and formatting
- Different size sensors
- ISO, Sensitivity and noise
- Low lightHigh
- ISO
- Noise
- Low ISO
- Noise and size of the sensor
In this lesson we are going to discuss the first 5.
The sensor of the digital camera, has the same function of a film, in a film camera
Phone camera sensors
A censor is where the lens of the camera drops the focus and where the image is captured, before it is converted to digital data and stored on the camera’s memory card.
1. The sensor consist out of:
The area of the sensor is covered with millions of microscopic “light reading” objects that are called photosites. Each of these represents 1 pixel of the image that is taken.
If we talk about a 10mp camera, it means that the cameras’ sensor consists of 10million photosites.
Photosite :
The photosite is found on the digital image sensor in a camera. The sensor array is made up of millions of individual photosites.Each sensor has a specific number of tiny individual sensors. Each is a photosite. For example, a Canon 5D MkII camera has a 21.1 MegaPixel full-frame digital sensor. In this case that is 5616 photosites wide by 3744 photosites high.
2. RGB
Photosites catches the light, but cannot distinguish between the different wavelengths – therefor in cannot capture the color.
To get a color image, a thin filter is placed over the photodiodes. This is known as the CFA – Color filter array.
This filter consists of a mosaic of RGB blocks of which each of them is placed on top of the photodiode. Now, each of the blocks can capture the intensity of the RGB.
The processor of the camera analyzes the color and intensity of each photosite and compares it with the one next to it.
3. Processing and formatting
As soon as this process is completed, the image undergoes more changes for example the colors, contrast and the sharpness of the image is improved. After this image is taken, the image is stored on the memory card of the camera.
4. Different sizes of sensors
The size of each camera’s sensor may differ. The physical size of the sensor is determined by the size of the individual photosite. To fit 12 million pixels on a small sensor, means that the photosites must be smaller. This also means that these “sites” are less sensitive to light, less contrast and that the probability of noise on the image is possible.
5. ISO, Sensitivity and Noise
With film photography, each film has a different ISO number. The ISO (International Standard Organization) determines how sensitive the film will be for light. The higher the number, the more sensitive it will be for light. The most common ISO number was 100 and 800 ISO was used for action photos.
The same is used in digital cameras. A dSLR camera has ISO settings of 100, 200, 400, 800, 1600 , 3200 and with “better” cameras even higher ISO settings. The higher the ISO is set, the more sensitive the sensor will be.
