Canon EOS REBEL T2I Instruction Manual page 30

Lens Peripheral illumination Correction
About the Lens Correction Data
The camera already contains lens peripheral illumination correction
data for approx, 25 lenses, In step 2, if you select [EnabJe], the
peripheral light correction will be applied automatically for any lens
whose correction data has been registered in the camera,
With EOS Utility (provided software), you can check which lenses have
their correction data registered in the camera, You can also register the
correction data for unregistered lenses, For details, see the Software
Instruction Manual (CDoROM) for EOS Utility,
@
For JPEG images already captured, lens peripheral illumination
correcuon cannot be applied.
Depending on shooting condltLons, noise m_ght appear on the image
Periphery.
When using a non-Canon lens. setting the correction to [Disable] is
recommended, even if [Correction data available] is displayea.
_t* Lens peripheral Hght correction is aoplJea even when an Extender is
attache(]
if the correction data for the attached lens has not been registered to me
camera, the result wiII be the same as when the correction is se-[ [o
[Disable]
The correction amoum applied will be slightly lower than the maximum
correction amount settable with Digital Photo Professional [prowaea
software)
If the ens noes no[ nave distance information, me correcuon amounz wHi
oe lower.
The higher the ISO speed, the lower the correction amount will be.
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