Okay – we now return you to our regularly scheduled 50D review series…
Today I’m taking a look at the Peripheral Illumination Correction feature. In short -most lenses will have a bit of falloff in the corners – a bit of vignetting. What Canon has done is to measure how much falloff there is in each of their lenses and have defined profiles for each. You can load up to 40 of them into the 50D (including combos w/ Canons 1.4x and 2x TCs) so that the camera can correct for this vignetting in the camera while it is creating the jpeg image, or can store that info in the RAW file for use by DPP.
The process of setting it up is pretty easy. Connect your camera to your computer with the USB cable, fire up the EOS Utility, choose "Camera settings/Remote shooting", then pic "Peripheral illumin. correct." from the "Shooting menu" and you’ll get a screen like this: (click to enlarge)
From here you can check your Canon lenses from the list (note the category buttons in the top right, to help you sort through the long list). If you own either (or both) of the Canon TCs, you should click the appropriate extender buttons in the bottom left. The list will re-populate with all the canon lenses that can use the TCs listed again with the TCs in combination. (note the top right column in the photo above). The bottom left corner of the window will let you know how many lenses you’ve selected out of the forty allowed.
Once you have your camera loaded with the profiles for your lenses – you are ready to go.
As a quick example – I’ve done a quick test with my EF-S 10-22, I shot a light colored wall to show the falloff, and then did a quick export from Lightroom. The top photo is the jpg (with the correction) the bottom photo is the RAW without.
The correction seemed to work pretty well in camera when shooting JPG. It didn’t eliminate the falloff completely, but it did a pretty good job. If the shot was not of an evenly toned light wall, you might not even notice that all the falloff wasn’t gone.
If you are a RAW shooter who uses DPP for their RAW processing, PIC will also work for you. When you review your image, DPP will let you know if PIC was on when a given image was shot. Below you can see a screen shot of some of the images I shot: (click to enlarge)
In the "frame" around each image, you can see an icon that looks like a white Canon lens. This indicates that the RAW image was shot with PIC enabled. From here you can turn off the correction, or can tweak it if you want. Choose "View" then "Tool Palette" from the menu and you will get the tool popup. Choose the "NR/Lens/ALO" tab, then click the "Tune…" button. You will get this popup: (click to enlarge)
If you want to turn off the correction, you can un-check the box next to "Peripheral illumination". The slider can also be moved to adjust the amount of correction.
I also worked with the images in Lightroom 2.1 release candidate – which has "preliminary" support for the 50D. As I expected, the correction did not import, but a quick click to "develop" then adjustment of the "vignette" slider, and the same end result was achieved.
Another quick note – I pulled the jpeg files that are embedded in the RAW file (as a preview) out and took a look at them to see if the PIC was applied to those JPGs…
I think this is a feature aimed at .jpg or DPP users, and seems to work okay for those uses. Being a RAW shooter who post processes in Lightroom, I’m planning to leave it turned off all the time. Not only won’t I use the data in LR, I don’t want the camera to create previews that don’t match the RAW files. The vignette tool in LR will do just fine for me.
Thanks for reading!