There are 2 types of lenses (very simplified):
- Lenses for full frame cameras
- Lenses for APS-C cameras
The 7D has a setting to correct the light fall off at the corners with the
Lens Peripheral Illumination Correction. Menu → 1st red camera tab, toward the bottom
Lens Peripheral Illumination Correction → the 7D will analyze the lens, and check if the data is available.
- The data is part of the firmware and is updated on regular basis by Canon with new firmware.
- The data covers most of Canon’s lenses. The keyword is most and doesn’t cover all of Canon’s lenses.
- The data covers very few very widely used non-Canon lenses.
This only applies to JPEGs and not to RAW
- There should be no lens peripheral illumination correction if you are using a full frame, EF, lens. The light fall off only happens at the edge of full frame, and the edge of the lens is cropped by the APS-C sensor.
- The lens peripheral illumination correction, should help with EF-S, cropped format lenses.
But, there’s always a but that makes it “kind of useless:”
- It only works for JPEGs. It can be useful when you need to deliver jpegs straight out of the camera without any processing, cropping…
The various processing software, like DPP, Lightroom, Camera Raw, Bibble, DXO… do a much better job of controlling the lens peripheral illumination correction.
- The processing software has a much more wide lens database. Lightroom covers over 1500 lenses/camera combinations, DXO even more.
- The processing software not only does the lens peripheral illumination correction, but the software also corrects many color aberrations and also corrects many lens distortions. Lightroom does a very good job and people have said that DXO does an outstanding/fantastic job.