stereo calibration intrinsics are different than single camera calibration

I have checkerboard data from two cameras. If I run the stereo calibration app and look at the calibration results for each camera the results are different than if I run the single camera calibration for each camera separately. The difference between the results is not within the error estimation.

Can anyone explain why there is a discrepancy between the two?

Thank you!

[Florian Morsch]

Do you use the same set of pictures for both calibrations? If you use different sets you also will get different values.

Answer 1

[Diarmaid Cualain]

I suspect that in stereo calibration, as both cameras are calibrated simultenously, one cameras calibratin might componsate for a slight-mis calibration of the other camera. This would result in different calibration values for a camera calibrated on its own vs. as a stereo pair. However, I would assume that the variance would be very small.