What does "sensor height" mean, and how do I find it for a phone camera?
Asked 7/17/2018
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I’m trying to use a formula that refers to a camera’s sensor height, and I’m not sure what that means in practice. Is it the physical height of the camera sensor’s active area?
For an LG G2 phone camera, I found specs listing a sensor format of about 1/3.06" and a 29mm equivalent focal length, but using 1/3" as a literal physical measurement gives results that seem far off. How do you determine the actual sensor height for this kind of camera, and are there any caveats when using a phone camera for measurement calculations?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
8y ago
2 Answers
6
Sensor height is indeed the physical measurement of the vertical dimension of the sensor's active pixel area.
From Wikipedia's Image sensor format article, the phone's sensor format of 1/3" (actually quoted as 1/3.06" in the LG G2 phonearena.com page you linked to) is 4.8 mm wide by 3.6 mm high.
I think the problem you encountered is assuming that 1/3" was a physical measurement; it is not. So-called 1 inch format (and fractions of it) is confusingly named, and has its roots in tube sensors that were used in broadcast TV. See also, Why is a 1" sensor actually 13.2 × 8.8mm?
Borrowing from @mattdm's deleted answer, regarding using camera phones as measurement devices,
[...] be aware that camera phones are not meant to be precision measuring devices, and many of the calculations tend to be of the "assume a spherical cow" sort (in this case, things like "assume a perfect thin lens and focus at infinity"). So even if you know the exact numbers, you might not be able to calculate distance to objects as nicely as you'd like.
Originally by user11924. Source · Licensed CC BY-SA 4.0
user11924
8y ago
0
Generated from our catalog & community — verify before relying on it.
Yes — "sensor height" means the physical vertical size of the sensor’s active imaging area.
The main confusion is that a sensor format like 1/3" or 1/3.06" is not the sensor’s literal physical size. That old "optical format" naming is historical and does not equal the real width or height.
From the answers, a 1/3.06" sensor is roughly in the range of about 4.8mm wide by 3.6mm high, though exact active area can vary. Another way to estimate it is from pixel pitch and image dimensions, if those are known.
Also, the listed 29mm focal length is a 35mm-equivalent value, not the actual lens focal length. The real focal length is closer to about 4mm.
So for formulas, use:
- sensor height = actual physical sensor height in mm
- focal length = actual focal length, not 35mm equivalent
Important caveat: phone cameras are not precision measuring instruments. Their focal length, distortion, focus behavior, and internal processing can make distance/size calculations inaccurate, especially away from the image center or at close distances. If you need reliable measurements, camera calibration is usually necessary.
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