Working with Lens Distortion on a Nikon DSLR
Certain lenses can produce a type of distortion that causes straight lines to appear curved in the photos you take with your Nikon D3100, D5100, or D7000. Wide-angle lenses, for example, often create barrel distortion, in which objects at the center of a picture appear to be magnified and pushed forward, as if you wrapped the photo around the outside of a barrel. The effect is perhaps easiest to spot in a rectangular subject like this oil painting. Notice that in the original image, on the left, the edges of the painting appear to bow slightly outward. Pincushion distortion affects the photo in the opposite way, making center objects appear smaller and farther away.
You can minimize the chances of distortion with your Nikon DSLR by researching your lens purchases carefully. Photography magazines and online photography sites regularly measure and report distortion performance in their lens reviews.
If you notice a small amount of distortion, try enabling the Auto Distortion Control option on the Shooting menu. This feature attempts to correct distortion as you take the picture. Or you may prefer to wait until after reviewing your photos and then use the Distortion Control on the Retouch menu to try to fix things.
The extent of the in-camera adjustment you can apply is fairly minimal. It’s also a little difficult to gauge results on the monitor of your D3100, D5100, or D7000, because you can’t display any sort of alignment grid over the image to help you find the right degree of correction.
All that said, the first step in applying either filter is to display your photo in single-image playback mode and then press OK to display the Retouch menu. Highlight the filter you want to use (Distortion Control or Fisheye) and press OK again. From that point, the process depends on which of the two filters you’re using:
Distortion Control: Select Distortion Control and then press OK. An Auto option is available for some lenses, as long as you didn't apply the Auto Distortion Control feature when taking the picture. As its name implies, the Auto option attempts to automatically apply the right degree of correction. If the Auto option is dimmed or you prefer to do the correction on your own, choose Manual. The little scale under the image represents the degree and direction of shift that you’re applying. Press the Multi Selector right to reduce barrel distortion; press left to reduce pincushioning. Press OK when you’re ready to make your corrected copy of the photo.
Fisheye: After you highlight the filter name and press OK, you see the word Fisheye at the top of the screen, and the scale at the bottom of the image indicates the strength of the distortion effect. Press the Multi Selector right or left to adjust the amount. Then press OK to create the fisheye copy.