Sometimes you look at a photo and you know something just isn’t right. If there is one thing that will cause that uneasy feeling, it is unfixed lens distortion in a photo. Our brain knows buildings have straight lines, faces have certain proportions, and animals don’t lean as they are standing. Curved trees, crooked buildings, or pinched faces – they all subconsciously scream “unnatural” to our brain.
Fortunately, there are many ways to fix lens distortions within the digital darkroom. In just a few clicks, using Lightroom‘s Lens Correction and Transform Panels, you can correct curved cathedrals, fun house faces, or bent buffalo!
A lens distortion causes straight lines in your photo to appear as curved. This occurs most often in wide angle lenses and in lenses with large ranges (especially at the far extremes), but can occur in any lens. The distortion is a factor of the physical construction of the lens, but can be exaggerated by the sensor size of your camera, and the focal length you are shooting at.
The two most frequent types of distortion are barrel and pincushion. Barrel distortion is when the straight lines in your photo curve out from the center toward the edges. This gets its name because your photo looks like it has been wrapped around a sphere or barrel. Pincushion distortion means your lines curve in toward the center. Think of it like pushing your finger, or a pin, into fabric. The cloth moves in toward the point you push. In the case of both distortions, the effect is usually symmetrical, and becomes more extreme the further you get away from the center of your shot.
Lightroom includes a library of lens specific profiles within the “Lens Correction” panel, applying the correct one based on the metadata embedded in your photo. These profiles fix a variety of issues, including vignetting, chromatic aberrations, and lens distortions.
While they do a good job overall, I am a firm believer in knowing when to take control away from the computer, whether it’s the one in your camera or the one you process your photos on. These silicon brains do some things extremely well, but when it comes to lens distortions, the adjustment often is not the right amount.
The Two Click Transform
New to the Creative Cloud versions of Lightroom is the Transform panel, which provides what Adobe calls the Upright Tool. This tool allows you to transform your photos in many ways, changing perspective and scale. The Upright Tool has a total of six buttons. Four of the buttons are for automatic perspective correction: Auto, Level, Vertical, and Full. When you click one of these, Lightroom will run a calculation on your image, and try to fix any perspective issues it calculates. There are also a number of sliders below these buttons you can use to tweak or override what Lightroom comes up with. The Off button turns off any transformations which have been applied, whether automatic or manual.
But, it’s the Guided button that is my favorite. This allows you to choose exactly how the correction is calculated by clicking reference points in your image.
To use this option, either click the Guided button or the “Upright Tool” icon in the upper left of the panel. Then choose something that has a strong line, like a building or tree, near the center of your photo. Click near one end of the object, and drag to the other end of it. Now choose a different line or object near the edge of your photo. Again click and drag from one end to the other. After you set the second guide, you will see your photo corrected according to the guides you just placed.
Lightroom compares the difference in angle between the two guides, and makes a correction and crop to adjust the distortion in your image. You can adjust this correction via the sliders just as you can with any of the other options. If it still doesn’t look quite right, you can click the Upright Tool again to move, delete, or add new guides.
Images with reflections are perhaps the easiest to correct. In my article “Straighten Your Photos with a “Reflection Correction“, I showed just how fast and easy it is to use reflections in your image to straighten a crooked photo. The same holds true for fixing lens distortion. When you place your guides, click at the top of an object, and drag to the same point in its reflection. This will give you the most accurate and level results!
According to Adobe, and from what I have found using these tools, you should apply the Lens Correction profile before you use the Transform feature. This sets a baseline for the calculations, producing better results.
As you click-through each Transform button, it will reset anything you have done with the Transform tool so far. It may also reset any cropping you have done, so cropping and straightening is best left until after you have made any distortion corrections.
The main problem with fixing a lens distortion is you are going to lose some of your original image. To deal with the distortion, Lightroom will stretch or shrink your shot, resulting either in it creating data to keep the original size, or cropping your photo to remove any extra canvas it adds. While this usually goes unnoticed in terms of image quality, the greater the distortion correction, the larger the crop will be.
Sometimes distortion is desirable, so don’t just automatically fix it in every photo. Think of distortion as a creative tool, sometimes you use it, sometimes you don’t. Making these types of creative choices is part of the fun of being an artist!
If you would like to read the official “how to” from Adobe, it is available here: https://helpx.adobe.com/lightroom/help/guided-upright-perspective-correction.html