How is lens selection connected to Image Sensor Format?
Updated: Dec 22, 2020
When we look at image sensor datasheets, we come across 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.
We come across sensor image format specs such as 1/3”, 1/4”, 2/3” and so on. How does this impact our lens selection? When we are selecting the lens, we come across lens specification termed LENS FORMAT. This specification also indicates numbers such as 1/3”, 1/4" etc.
Ideally, we need to ensure that the sensor image format and the lens format matches. However, there are scenarios where we do not get exact match when we bring in lens specification requirement such as FOV, Focal length, resolution etc. When we do not get an exact match, then we should follow the below thumb rule
→ Larger Format lenses can be used on smaller format sensor.
→ Smaller format lenses cannot be used on larger format sensor.
For example, should you be choosing the IMX290 Sony sensor based camera module, then we have an understanding that the sensor size is 1/2.8”. The lens we choose should be of lens format of either 1/2.8” or larger such as 1/2.5” or 1/2.3” etc.
Another example we can look at is the AR0521 On Semiconductor sensor based camera module. The sensor size in this case is 1/2.5”. We should work on selecting a lens that has lens format of either 1/2.5” or larger such as 1/2.3” or 1/2" etc.
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