This month I received a technical question from pro photographer Johnathan Esper who asked:
“How do you blend the sky so well in your stitched panoramas? I mean, when I am including sky in images, especially when using a polarizer filter, and despite all precautions including full manual control during exposure, and vignetting reduction prior to stitching, I get dark and light banding in the blue sky. I am stuck in Photoshop using clone tool, burn and dodge tool, shadow/highlight tool to all help even out the tone differences in the sky, but nothing’s perfect.”
This is a common problem with stitched images involving lots of blue skies. Stitching is the technical term for taking several photos of a scene while the camera is moved along a single axis, usually horizontally. Here are some ways to improve your panoramas…
As far as the sky, one tip I can give you is don’t use a polarizer. If you’re looking for seamless blends, a polarizer will have the opposite effect. Because a polarizer has the strongest effect when the camera is facing 90° to the sun, this will create uneven tones in the sky as you pan the camera to create the panorama.
You will end up spending hours in Photoshop trying to blend your skies, and while possible using gradients, I’d rather get it right in the camera. You’re better off creating the entire image first without the polarizer, then adjusting the sky afterwards, perhaps using the excellent HSL controls in Lightroom or Camera RAW.
Another tip is not to shoot at the shortest focal length of your lens which is where most of the vignetting occurs. Most lenses are weakest at their extreme settings (shortest focal length or maximum aperture) so I avoid these when possible. On my Canon 17-40L wide angle lens for example, I’ll use anywhere from 19-30mm depending on the subject, and manage to avoid most vignetting issues. Finally make sure you are overlapping the shots by 20%-30% which will eliminate most edge issues such as softness and vignetting. This will also give you better results when you start to stitch the images.
For those curious about stitching software, Photoshop CS4 has a pretty good Photomerge feature that works very well with most images, and has been improved from previous versions. Dedicated stitching applications offer more features and generally better results. These include:
- AutoPan Pro – also feature rich and excellent results.
All of these are dedicated commercial applications, so if you are just getting started, I recommend Hugin , which is free and available for both Mac and Windows. Finally, if you have an iPhone, you can try TripStitch which allows you to create large panoramic photos in the field!
Thanks Jonathan for the great question, and please keep them coming.