- Capturing the image
- Camera settings
- Care and maintenance
- Custom functions
- Digital camera features
- Digital image file
- Digital image size and preview
- EOS MOVIE
- Exposure settings
- Flash basics
- Speedlite compatibility
- Speedlite range
- Speedlite zoom
- Flash on camera
- Dark backgrounds with flash
- Fill in flash
- Flash exposure lock and compensation
- Wireless flash
- Macroflash photography
- Bounce flash
- Flash synchronisation
- Stroboscopic flash
- Studio-style flash lighting with Speedlites
- Integrated Speedlite Transmitter
- Remote Release
- Focus points
- Image download
- Image compression
- Image information
- Image verification
- Introduction to digital photography
- Focal length
- All about apertures
- Lens speed
- Focusing and depth of field
- Black or white lenses
- Coloured rings
- Lens mount
- EF-S and field of view
- L-series lenses
- Fluorite, aspherical and UD lenses
- Prime and zoom lenses
- Image stabilisation
- Tilt and shift lenses
- Extension tubes
- Macro lenses
- Close-up lenses
- DO elements
- Fisheye lenses
- SubWavelength structure Coating
- Media cards
- Panoramic images
- Remote photography
- Scanning & copying
- Storage and archiving
- The digital darkroom
- White balance
Panoramic images: Creating panoramics
Sometimes, even the widest-angle lens isn’t enough to produce the view you want. An ordinary wide-angle shot can work well, but you can emphasise the sense of width a landscape conveys by creating a panoramic shape that is much longer and thinner than an ordinary 35mm frame format. In the days of film, to create your panorama you had to shoot lots of images, stick the prints together and then re-photograph them as a whole. With digital though, it’s much easier – and the results are usually better. All you need is PhotoStitch software, which is on the EOS Digital Solutions disk supplied with every EOS digital camera.
How does it work?
While it is possible to assemble the photographs using a pair of scissors and paste, PhotoStitch software does all the hard work for you, aligning the images and making sure they fit together properly. To join the images together, PhotoStitch examines each one and finds areas of overlapping similarity between adjacent pictures. It then merges the images together to create as seamless a join as possible. If a slight join is visible, you can edit it out in Photoshop, or a similar imaging program.
As with any photograph, the first thing you need to decide is which lens is going to work best for the shot you are hoping to produce. Shooting images to stitch into a panorama is no exception. Which lens will give you the field-of-view, either horizontal or vertical, to include the parts you want in the shot? Your lens choice, and the resulting field-of-view, will also determine the number of shots you need to take to complete your panorama.
At this point, you also need to choose whether you are going to shoot with your camera in landscape or portrait format. Shooting a horizontal panorama in portrait format will mean you have to shoot more images than if you shoot it with the camera in landscape format. This will mean more stitches, any of which may be visible in the final image. However, the bonus of shooting in portrait format is that you have a greater vertical field-of-view – you can include more sky and foreground in your image. On the downside, you will have a larger image to work with afterwards.
How many shots?
The number of shots you need to create your panorama is determined by four factors:
1 - the lens focal length.
2 - whether you choose to shoot in landscape or portrait format.
3 - how much overlap you want to have in each shot.
4 - how wide you want the final image to be.
For optimum stitching, and the best final image, you need the images to overlap sufficiently for PhotoStitch to find similar points and match them up correctly. By overlapping your images by between one-third and one-half frame, the software is able to match up pixels accurately.
Your choice of shooting format will depend on how you envisage your final image. Generally, most people shooting landscape panoramas choose to shoot in vertical format to achieve a greater vertical field-of-view. It means stitching together more shots than if you shoot horizontally, but will give you a larger final image.
Your lens choice will also affect the number of shots you need to take. The wider the lens, the fewer images you will need to complete the panorama.
Generally speaking, panoramas are shot on fairly wideangle lenses, from about 50mm to 20mm. If you use anything wider than a 20mm lens, PhotoStitch cannot stitch the images.
The final piece of the puzzle is how wide a field-of-view you want your panorama to cover. The wider the scene you want to capture, the more images you will need to complete the shot.
There is a simple calculation that will tell you exactly how many shots you need to take to complete your panorama, depending on lens choice and required image overlap. From here it is easy to calculate the angle you need to turn the camera between each shot and achieve your desired result.
The calculation is this:
Number of images = (100 x A) / (100 – B) x HFOV
Where A = the angle-of-view of the panorama you want to create (180° for example) and B = the percentage overlap you want (50% for example). HFOV is the horizontal field-of-view of the lens you are using. If the camera is used in portrait format, then the horizontal field-of-view is the vertical field-of-view of the lens.
As an example, assume you want to capture 180° panorama using a 28mm lens in portrait format with a half-frame overlap using an EOS 5D. The field-of-view of a 28mm lens is 65° horizontally and 46° vertically. This means in portrait format, the horizontal field-of-view will be 46°.
If you wanted no overlap of adjacent images, you could complete the 180° view with four images. However, by overlapping by half a frame for each shot, you are effectively halving your horizontal field-of-view, so in fact you need eight images to create a full 180°. But how do you know what half-a-frame overlap is? You could simply look through the viewfinder and guess, but the more accurate method is to use a graduated panoramic base on your tripod and rotate this by a set number of degrees each time. To calculate what this degree value should be, simply divide the width of panorama you want by the number of shots you need to take. In this example, that would be:
180/8 = 22.5°
This is too accurate, and since most panoramic bases are not graduated in single degree increments, you could choose anything between 20°, which would give you greater overlap, and 25°, for less overlap, and notice no difference in results. If you choose 20° you will need to take one extra shot just to make sure you complete the full 180°.
Making your first PhotoStitch panorama
1. Open the software. You will see an empty window. Click ‘Open’. You will be able to search your computer hard disk to find and select all the images you want to stitch together. If the images are not in the correct order, click ‘Arrange’ and drag them as required. PhotoStitch stitches from left to right so your images need to be in that order.
2. Select the merge tab and click ‘Start’. The program will start stitching the images together. Depending on the images, this can take a minute or more.
3. Select the Save tab and click ‘Save’. PhotoStitch will automatically create a squared border for the merged image, but you can click and move this as required.
4. Open and print the saved file. You have stitched your first panorama!
If this sounds very simple, it’s because it really is. However, although those three steps will get you a panoramic image, there are a few other features of PhotoStitch you should be aware of.
Although you are most likely to want to produce a long panoramic with PhotoStitch, the software can also produce a full 360° QuickTime VR movie clip, or create one large image from several smaller ones in both horizontal and vertical planes – like a patchwork quilt. You can select these options at the point of saving (for the 360° panorama) or in the merge settings (for the patchwork quilt effect, which is called parallel camera movement). When you are in the merge settings, you will also notice a menu to enter the focal length of the lens used. The software should auto-detect the focal length, but if it doesn’t, or you want to make sure it gets it right, you can manually input a 35mm equivalent focal length. For example, if you are using an EOS 30D with a 50mm lens, the field-of-view equivalent for a full-frame 35mm camera is 80mm, so you should enter 80mm as the focal length of the lens used.
Setting the camera and tripod
It is possible to shoot panoramic images quite successfully without using a tripod. However, for the very best images you should take a more controlled approach and keep the camera level. A tripod not only enables you to measure the rotation accurately between each shot, so you don’t have to leave it to guesswork, it also allows you to use a slower shutter speed. This means you can use a smaller aperture to achieve greater depth-of-field in your images.
Levelling up the camera
To get the best from your tripod, you can’t simply place it down and put the camera on top. You need to make sure the tripod itself is level first. Some include a bull’s-eye spirit level – if yours doesn’t, then you’ll need to improvise by attaching one. Alternatively, you could fit a levelling base to your tripod which will ensure that even if the tripod itself is not quite level, you can make adjustments until it is.
As well keeping the tripod level, you need to make sure the camera is mounted squarely on the tripod head, and that the head itself is level. Again, some tripod heads include a spirit level of some kind, if not, you can buy a hot-shoe mount spirit level that attaches to the camera.
If you are shooting in portrait format, you also need to be aware of the pitch and roll of the camera body. The roll is the angle that can be created when you use the camera in a portrait format. If you are not using the camera at exactly 90°, each image will be slightly rotated, making it harder to stitch together. It will also mean you will have to crop the final image more heavily to counteract the resulting downward slope.
The pitch is the angle of the camera back in relation to the horizon. Again, it should be 90° to avoid problems. If the angle is not 90°, images will be slightly trapezoidal. That is, they will be narrower at either the top or bottom than they are at the other end, depending on whether the camera is angled up or down. Although you may still be able to stitch images together, a large deviation from 90° will make it impossible to get a perfect stitch.
Understanding nodal points
You should apply the same compositional rules when you're shooting panoramas as you do when photographing an ordinary landscape. Don't simply rely on the extra size of the panorama to give the image its impact.
A strong foreground subject can lift the composition, but this in itself presents a problem to successful stitching. When you have an object in the foreground, unless you rotate around the optical centre of the lens-camera combination, there can be a slight change in perspective between near and far objects as you turn the camera. Due to a slight shift in parallax, this can lead to alignment problems when you come to stitch the images together. It can create ghosting, where there appears to be two images of one object. To overcome this effect, you need to use a panoramic head to allow enough camera movement to centre the nodal point of the camera and lens over the point of rotation. The nodal point is the point within the lens-camera combination at which the light rays converge and cross. It is the optical centre of the lens.
Unfortunately, there is no simple calculation that helps you find the nodal point; it must be done completely by eye. However, when you look through the viewfinder you can see the changes that occur as you move the nodal point around. With the camera set up, look through the viewfinder and pan the camera around. If the nodal point is aligned properly, there should not be a shift between foreground and background subjects as you rotate around your panorama.
Panoramic exposure problems
Once everything else is set up and ready to go, the final thing you need to think about when shooting panoramas is the exposure.
As with any photograph, a good panorama should be correctly exposed and, ideally, the exposure should not change between each shot that makes up the panorama. In reality, however, a change in view can produce a wildly different lighting situation, which requires a very different exposure. You should use the same exposure for every image that makes up the panorama - this means you need to set the exposure manually on the camera so it cannot change.
If you are creating a full 360° panorama, then you will almost certainly be faced with shooting both with the light, and into the light. This will create some difficulties in exposure, since some areas need less exposure than others.
However, you can't simply adjust the exposure as you pan around the scene, as doing so will make it very hard to stitch images together and you could end up with big jumps in exposure across the image.
If you do plan to shoot a full 360° panorama, then you need to take one meter reading for the brightest sections and another for the darkest sections, then manually set an average exposure for the whole panorama. This will result in a reasonable compromise for the exposure of every shot within the panorama, though it may not be perfect for each.
If you're feeling adventurous, try shooting an exposure bracketed sequence of images at each point around your panorama, then combine them in your editing program to even out the exposure.
If you are creating a narrow panorama, it is unlikely that you will be faced with such varied lighting conditions, but you still need to be aware of instances when the light is changing rapidly - clouds moving quickly across the sky, for example - as this will cause problems with stitching later on.
Changing the white balance
For best results when stitching panoramas, you need consistency between each shot in the series. This means not only getting the exposures consistent, but also the white balance.
If you leave the camera on auto white balance, it will make the necessary adjustments for each exposure. If you are shooting RAW, you can rectify the problem by matching the white balance in each shot during the RAW conversion process. However, if you're shooting in JPEG, you need to get it right in camera at the point of shooting, otherwise it will be hard to correct afterwards. This means setting the white balance manually. Either pick a setting that is appropriate, like daylight or tungsten, or for even more accuracy, set a custom or Kelvin value to ensure there is no change at all between each exposure within the panorama.
Hyperfocal distance focusing
It is best use manual focusing when shooting panoramas. Autofocus will alter the image slightly each time and you will find it difficult to obtain a clean stitch. You need to set the hyperfocal distance on the lens to make sure you have as much depth-of-field as possible, and that it is consistent for each shot in the series that you're stitching.
The hyperfocal distance at a given aperture is simply the distance at which you have maximum depth-of-field in an image. In general, when photographing a landscape, you should focus one third of way into the image as this usually gives sufficient depth-of-field. However, if you want to be as accurate as possible and achieve the absolute maximum depth-of-field, you need to focus at the hyperfocal point.
This can either be calculated or obtained from depth-of-field tables. By focusing at the hyperfocal point, you will achieve the same depth-of-field in every image of your panorama. This will make stitching easier and provide more successful results.
If you are photographing indoors, however, you don't often require the depth-of-field to extend to infinity. In this situation, you can use a wider aperture or focus somewhere other than the hyperfocal distance. You should still use manual focus, though, as you don't want the focus distance to change between shots.
Hyperfocal distances table (metres) - select your focal length on the top row and your aperture down the side
The tables below show the horizontal field-of-view for each lens (depending on format) and how many images are needed, based on a 180° panorama. If you are shooting in horizontal format, use the first table; if vertical, use the second table. Format refers to the camera position when shooting - not the shape of the finished panorama. Rotation refers to the number of degrees you need to pan between each exposure. Images refers to the number of images required to complete the 180° panorama.
Horizontal format shooting table
|FOV||overlap of 1/3||overlap of 1/2|
Vertical format shooting table
|FOV||overlap of 1/3||overlap of 1/2|