Canon EOS 90D Advanced User's Manual page 209

Chromatic Aberration Correction
Chromatic aberration (color fringing around subjects) can be corrected.
[Chromatic aberr corr] is not displayed when [Digital Lens Optimizer] is
o
enabled.
Diff raction Correction
Diff raction (loss of sharpness caused by the aperture) can be corrected.
Depending on shooting conditions, noise may be intensifi ed together with the
o
eff ects of correction.
The higher the ISO speed, the lower the correction amount will be.
o
For movie recording, [Diff raction correction] will not appear. (Correction is
o
not possible.)
With "Diff raction correction", degraded resolution due to the low-pass fi lter, etc.
o
is corrected in addition to diff raction. Therefore, correction is eff ective even at
an aperture close to the open aperture.
[Diff raction correction] is not displayed when [Digital Lens Optimizer] is
o
enabled.
Correction of Lens Aberrations due to Optical Characteristics
209