Peripheral Illumination Correction on Canon Rebel T3 Series Cameras
The Canon Rebel T3 and T3i offer Peripheral Illumination Correction, which adjusts image brightness around the edges of the frame. Some lenses produce pictures that appear darker around the edges of the frame than in the center, even when the lighting is consistent throughout. This phenomenon goes by several names, but the two heard most often are vignetting and light fall-off. How much vignetting occurs depends on the lens, your aperture setting, and the lens focal length.
Now, this before example hardly exhibits serious vignetting — it’s likely that most people wouldn’t even notice if it weren’t shown next to the after example. And frankly, you’re not likely to notice significant vignetting with the 18-55mm kit lens bundled with the camera, either. But if your lens suffers from stronger vignetting, it’s worth trying Peripheral Illumination Correction.
The adjustment is available in all your camera’s exposure modes. But a few factoids need spelling out:
The correction is available only for photos captured in the JPEG file format. For Raw photos, you can choose to apply the correction and vary its strength if you use Canon Digital Photo Professional to process your Raw images.
For the camera to apply the proper correction, data about the specific lens must be included in the camera’s firmware (internal software). You can determine whether your lens is supported by opening Shooting Menu 1 and selecting Peripheral Illumination Correction.
If your lens isn't supported, you may be able to add its information to the camera; Canon calls this step registering your lens. You do this by cabling the camera to your computer and then using some tools included with the free EOS Utility software, also provided with your camera.
For non-Canon lenses, Canon recommends disabling Peripheral Illumination Correction even if correction data is available. To turn off the feature, select the Disable setting. You can still apply the correction in Digital Photo Professional when you shoot in the Raw format.
In some circumstances, the correction may produce increased noise at the corners of the photo. This problem occurs because exposure adjustment can make noise more apparent. Also, at high ISO settings, the camera applies the filter at a lesser strength — presumably to avoid adding even more noise to the picture.