The actual optical system cannot achieve strict temperature compensation, that is, in a certain temperature range, the image surface of the system cannot be consistent with the change of the lens barrel with complex structure, which requires an Error tolerance for temperature compensation.

In a broad sense, the image defocuses caused by temperature can be regarded as a kind of aberration. According to the Rayleigh law of optical system aberration, the temperature compensation error should be controlled at its maximum wave aberration less than 1/4 wavelength.