Sensor Image Format - Size of the sensor
Updated: Dec 22, 2020
This article talks about the specification we come across in sensor datasheet called the Image Format. We come across this specification that talks about image format being 1/3” or 1/2.3” and so on. What does this indicate?
This number indicates the diagonal measurement of the active image size on the sensor. The inch referred to here is the optical form factor. 1” optical form factor is 16mm. This is derived from the times where we used tube cameras where image format of a tube placed in a 1” deflection coil was called 1” format.
The common formats that we come across are
How does the sensor size impact us?
When we choose the sensor, we need a keep a watch on the sensor size. The sensor size determines the
1. Resolution – The resolution of the sensor is the number of pixels that the sensor supports. The number of pixels and the size of each pixel is determined by the sensor size.
2. Sensitivity – As mentioned above, the pixel size and number of pixels is tightly integrated with the sensor size. The pixel size determines the effectiveness of the pixel to accept the photons falling on it during exposure and that in turn decides the sensitivity of the sensor to light.
3. Optics – The size of the sensor decides its compatibility with various optics standards such as M4, M6, M7, M8, M12 and C/CS mount. The optics diameter cannot be lesser than the sensor diagonal.
To explain with examples, when we are looking at requirements demanding us to have a camera that is as compact as possible and supports higher resolution, we are looking at solution option that can support
1. Higher resolution – 4K or 13MP
2. Compact Optics – M6 standards with 6mm diameter
This leads us to an 8MP or 13MP sensor that has a sensor size of 1/3” or lesser as optics diameter is 6mm. We have worked with options such as AR1335, OV13850 based camera modules.
Another scenario, should the requirement demand the need for a low light camera with wide field of view, then we are looking at a solution option that can support
1. Higher pixel size and Higher sensor size
2. Limited Resolution à 2MP or 3MP would be sufficient.
3. M12 Standard as we have many FOV options to choose from.
This leads us to a 2MP or 3MP sensor based camera with a M12 lens holder and Wide FOV lens. We have worked with options such as IMX290, IMX390, AR0330, AR0230, AR0233 based camera modules.
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