Keystoning: What is it, how to avoid it, and one way to fix

Keystoning: What is it, how to avoid it, and one way to fix

As a photographic judge for PPA, states and International organizations I get to see a lot images. One problem for wedding and architectural photographers is keystoning. When the vertical lines in your image point toward each other, that’s keystoning.

Let’s talk about how to avoid and/or fix this problem. You can also leverage the effect for creative imagery. But that’s for another article.

Keystoning in photography

Keystoning is apparent when you tilt the camera up, or down, and vertical lines converge. This is more apparent when you use wider angle lenses. Or as you are closer to the vertical lines. The larger the tilt, either up or down, the greater the effect.

Tilting the camera up will make the verticals converge as the bottom of the image is closer to the sensor than the top.

Let’s get a little technical about it the effect. Magnification between the area closest to the lens sensor is quite different than further. This results in the extreme tilt/convergence. Know that once you are aware you can find ways to keep this from creeping into your photo. This is absolutely a ‘What you see is what you get’ phenomena.

1709126414 62 Keystoning What is it how to avoid it and one | Theedgesm
Tilting the camera down will bring your verticals closer together at the bottom of the photo. The effect is magnified when using a wide angle lens or with greater tilt.

Avoiding keystoning

Ideally you can avoid the keystoning from happening in your image by keeping the lens perfectly vertical in relation to your subject. Use a longer lens from further away. Not able to do either of these things because you are on a city street or for compositional reasons? Do not fear this can be fixed, or at least mitigated, in post production.

1709126414 980 Keystoning What is it how to avoid it and one | Theedgesm
Camera lens was vertical and parallel to the scene hence no converging lines.

Photoshop guides

An aid to getting your lines straight is Guides. You get guides by clicking and dragging in the Ruler. If the Ruler is not showing you can press Cmd > R Mac Crtl > R PC and the rulers will appear or disappear. Drag from the top Ruler for horizontal Guideline and from the left side to get vertical guide lines. Each time you click and drag you can add another guide. If you would like to hide the guides without removing them from your image Cmd > H Mac Crtl H PC will toggle them on and off. Once you have your guides set it’s time to transform.

1709126414 190 Keystoning What is it how to avoid it and one | Theedgesm
1. Once the Transform tool has been activated pulling on any corner will cause the opposite corner to move as well. 2. Click and drag on the top ruler to access a horizontal guide. 3. Click and drag to access a vertical guide. You can pull as many guides as needed but the three you see here is my go-to.

Photoshop Transform Tool

Transform tool is your friend. Many programs have transform tools. Here is how I work in Adobe Photoshop. Open the image. You will need to click the Lock on the background layer to allow it to be transformed. Another possibility is to copy the the layer and perform your transformation on the layer verses the entire file. Menu Edit > Transform > Perspective. Using Perspective means holding one corner and moving will move the other corner the same distance at the same time. Should you need to move only one side of the image at some point you can use the Skew option and only one side of the photo will be adjusted.

1709126414 299 Keystoning What is it how to avoid it and one | Theedgesm
Here is the image corrected for converging lines with the camera tilted up. It has a bit of distortion from the fix, but in my opinion way better than the converging lines.

Watch for this phenomena while you are making your photograph and you will have to deal with it less. If it’s unavoidable, now you know how to fix it!

Yours in Creative Photography, Bob