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I am trying some 3D scene reconstruction in blender using my phone camera but in order for the program to do its math it needs to know the sensor width and focal length of my camera in millimeters but I have no idea of where I can get those values, all I know is that its a "f2.2 1.25-micron" camera but I have no idea of what that means.

Some estimations using another software tell me that it's between 23mm and 27mm focal length if it was a 32mm sensor but I need a more accurate range.

My phone is a Redmi-6A.

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The Redmi 6A uses the Sony Exmor IMX486 sensor, which is a 1/2.9" format sensor. Note that "1/2.9 inch" is merely a name, not its diagonal dimension (see: Why is a 1" sensor actually 13.2 × 8.8mm?).

The IMX486 has a 5.04 mm × 3.77 mm sensor, corresponding to a crop factor of about 6.9×. The camera's focal length is about 3.8 mm (actual), which is about 26 mm (35mm camera equivalent).

To find these values, you have to search for terms such as "redmi 6A sensor dimensions", or the like. I have found that most sites often don't return detailed information about the sensor used in Asian-market phones. But you just have to go through the search results until you find details such as which actual sensor chip is used (such as the Sony Exmor IMX486), and then look up the sensor's specifications, such as "Exmor IMX486 dimensions".

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  • \$\begingroup\$ Thanks 26mm worked perfectly for the 3D reconstruction. \$\endgroup\$
    – Jeacom
    Commented Jul 10, 2020 at 2:15
  • \$\begingroup\$ As an aside, that shows the software estimations were remarkably good \$\endgroup\$
    – Asteroids With Wings
    Commented Jul 10, 2020 at 12:56
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That information tends to be in the EXIF information of any JPEG you create using this phone. Programs like Exiftool can be used to read them out, but many image viewers are also able to display that kind of information as "Details" or similar.

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    \$\begingroup\$ I tried it and the exif data says my focal length is 3.8mm but doesnt says whats the sensor size, so I have no idea of how to proceed. \$\endgroup\$
    – Jeacom
    Commented Jul 9, 2020 at 22:53
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    \$\begingroup\$ @Jeacom, EXIF might also give you the 35mm equivalent focal range. From which you can compute the sensor size. I do not know whether that would have been accurate enough. Also, I am not sure how the 35mm equivalent focal range is computed if the aspect ratio is not 3:2. \$\endgroup\$
    – Carsten S
    Commented Jul 10, 2020 at 14:25
  • \$\begingroup\$ @CarstenS usually based on the image diagonal. \$\endgroup\$
    – hobbs
    Commented Jul 11, 2020 at 3:48

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