Canon EOS REBEL T2I Instruction Manual page 29

Lens Peripheral illumination Correction _
Due to the lens characteristics, the four corners of the picture might look
darker. This is called lens light fall=off or drop in peripheral illumination.
With JPEG images, the correction is done when the image is captured.
For RAW images, it can be corrected with Digital Photo Professional
(provided software).
The default setting is [EnabJe].
Correction enabled
,_ Setect [Peripheral illurnin.
correct.].
® Under the [t_'] tab, select
[Peripheral illumin, correct.], then
press < _ >=
*),_,_Set the correction setting.
® On the screen, check that the
attached lens' [Correction data
available] is displayed=
® if [Correction data not available] is
displayed, see "About the Lens
Correction Data" on the next page=
® Press the <A_'> key to select
[EnabJe], then press <_>.
_ ake the picture.
® The image wiii be recorded with the
corrected peripheral illumination=
104
Correction disabled