Photography tips: stitching for panoramas
DIGITAL STITCHING was first used to create large files sizes from a small file size camera. Compared to large-format or 6x17cm films, the 3- or 6-megapixel sensors of five to ten years ago simply didn’t have the resolution or clarity needed to make enlargements.
However, while one frame wasn’t enough, it was possible to take a series of exposures and join them together. The resulting file could be as large and as detailled as you wanted it to be, although some post-production was needed.
Today, digital cameras have solved the resolution problem, yet stitching remains a popular project. It allows you to create some massive file sizes that could happily be printed to the size of a house, but perhaps more importantly, they allow us to capture a perspective that is engaging and aesthetically pleasing: the panorama.
Stitching with a digital camera allows you to capture panoramas as wide or as long as you like – well, up to 360° at any rate! It means you can visit a location and create something that is impossible with a single exposure on a normal digital camera.
Panorama, Hill Inlet, Whitsunday Island. This and top photo by Peter Eastway
Whether for large file sizes or a new aesthetic, stitching can be a lot of fun, but there are a few things to keep in mind, at least when you’re starting off, to ensure you produce the perfect stitch.
Fortunately, you don’t need specialist equipment to make it work, although you can certainly buy specialist equipment to make the process easier and more accurate.
Here are my top tips and tricks to help you:
1. Manual exposure
When taking a series of stitching images, ensure you set the camera to manual exposure. Variations in the brightness of the scene will produce variations in exposure if you leave your camera set to any automatic mode. This causes problems when you stitch the images together – they may align perfectly, but it’s not much good if one part of the image is light and the other part is dark. For seamless stitches, ensure your camera is set to manual exposure mode.
2. Manual focus
Just as your exposure can change as you pan the camera to capture the stitch images, so can the autofocus be fooled into focusing on something you mightn’t be expecting. You don’ t have to manually focus the lens initially – you can use the autofocus system to lock in the focus as required, but then carefully turn off the autofocus (usually a switch on the camera body itself, so you shoudn’t accidentally move the focus setting). Don’t forget to turn it back on afterwards!
3. Manual white balance
If you’re shooting raw files, then this setting isn’t so important because you can adjust the white balance setting at the time you process the files. However, if you’re shooting JPEGs, then it’s important to maintain a consistent colour balance in all of the exposures. For the same reason we use manual exposure mode, select a manual white balance setting, such as daylight or tungsten. This can still be a good idea for raw shooters as many raw processing programs use the camera’s settings as a starting point for processing the file.
4. Overlap exposures
Stitching software needs to identify and locate points in one image that match points in the next time. For this reason, you must overlap your frames so there’s plenty of points to use. In a scene with lots of detail, less overlap is required to obtain a stitch, but there are other reasons for having an overlap of 30 to 40 percent. Lenses can suffer from vignetting, so the edges of the frames can be darker than the centre and this can make it difficult to produce a seamless stitch. The greater the overlap, the better the stitching software can perform.
5. Use a tripod
It is possible to take great stitched panoramas with hand-held exposures. Modern stitching software does an excellent job of putting the images together, but you will achieve superior results more often if you align the individual exposures as accurately as possible. This means using a tripod. When selecting a tripod head, a ball head will allow you to easily level the camera, even on uneven terrain, while a rotating plate on the top of the head facilitates stitching.
6. Shoot vertically
It might seem counter-intuitive to position your camera vertically to create a horizonal panorama, but this is good advice especially if you’re taking a number of frames. Often a series of horizontal frames when stitched doesn’t give you sufficient area above and below the horizon. The stitching process can mean you lose more image area than you might think, so the vertical format ensures you get more sky and more foreground. You can always crop it off later, but it’s much harder to add it in!
7. Stitch them together
This isn’t really a camera technique – it’s what you do after you have captured your raw material (the individual shots for stitching). Although Photoshop isn’t the only program that stitches images together, the techniques it uses are found in other programs as well. The latest versions of Lightroom also have stitching included.
Basically, in Phototshop, there are five stitching techniques offered, plus an Auto option. They cover the majority of situations you’re likely to encounter, although there will be times when Photoshop doesn’t perform as expected no matter which option you choose. In such situations you may have to use a different program, such as PTGui, to get an acceptable result – it seems the mathematics behind the stitching, even if based on similar principles, have slight variations. An image that can be stitched in Photoshop might be problematic in PTGui, and vice versa.
How do you do it? It’s really very straightforward. In your stitching software of choice, open up the program and select the shots you want to stitch together. Use the automatic settings to begin with and you have a 95% chance of success the first time – especially if you have followed the first six techniques correctly! Good luck!
Sydney-based photographer Peter Eastway is a Grand Master of Photography and a two-time winner of the AIPP Australian Professional Photographer of the Year.