Automatic lens corrections
I began this section on the Lens Corrections panel by showing you how to use the manual correction sliders because this seemed the best way to introduce you to what these controls do and why you would need to use them. When you use Lightroom 3, you will notice that the Lens Corrections panel defaults to showing you the Profile tab mode, shown in Figure 6.57, which now allows you to apply instant auto lens correction adjustments. This can be done with any image, providing there is a matching lens profile in the lens profile database that was installed with Lightroom 3. If the lens you are using is not included in the camera lens profile database, you will need to use a custom lens profile. I’ll come on to this shortly, but assuming there are lens profiles available in Lightroom 3 for the lenses you are shooting with, it should be a simple matter of clicking the Enable Profile Corrections box to apply an auto lens correction to a selected photo. When you do this, you should see the Make of the lens manufacturer; the specific lens Model and lens Profile (which will most likely be the installed Adobe profile) appear in the boxes below. If these don’t respond, then you may need to proceed to first select the lens manufacturer brand from the Make menu, then the lens Model, and finally, the preferred lens Profile.
Figure 6.57 The Lens Corrections panel showing the Profile tab options, with the Enable Profile Corrections box checked.
An auto lens correction will consist of three components: a Distortion correction to correct for the barrel or pin-cushion geometric distortion, along with the Chromatic Aberration and Vignetting corrections that I have just described on the preceding pages. The Amount sliders you see here allow you to fine-tune an auto lens correction. So, for example, if you wanted to allow an automatic lens correction to automatically correct for the chromatic aberration and lens vignetting, but not correct for, say, a fish-eye lens distortion, you could drag the Distortion slider all the way to the left. On the other hand, if you don’t believe an auto lens correction to be strong enough, you can easily increase the correction amount by dragging any of these sliders to the right.
The default option for the Setup menu is Default. This instructs Lightroom to automatically work out what is the correct lens profile to use based on the available EXIF metadata contained in the image file, or use whatever might have been assigned as a “default” lens corrections to use with this particular lens (see below). The Custom option appears only if you choose to override the auto-selected default setting, or you have to manually apply the appropriate lens profile. As you work with the automatic lens corrections feature on specific images, you will also have the option to customize the Lens Corrections settings and use the Setup menu to select the “Save new Defaults” option. This allows you to set new Lens Corrections settings as the default to use when an image with identical camera EXIF lens data settings is selected. As I mentioned above, in this instance, the Setup menu will also show Default as the selected option in the Setup menu.