While our workshops primarily focus on night photography, we get a lot of questions about how to capture a good panoramic sequence. This may be because it's a common technique for reducing noise or because it's a great way to capture a scene with the Milky Way arcing across the sky but regardless I wanted to share some of our favorite techniques for capturing a great panorama.
Which Lens Should I Use?
A lot of this decision is left up to the artist and his/her vision for a photograph but we recommend anything from a 14mm to an 85mm focal length. Generally speaking, a longer focal length (35mm or 50mm) will mean more images in the sequence which will result in better quality in the final results. A shorter focal length (14mm or 20mm) will result in more distortion which may make the frames more difficult to stitch together but it will need fewer images in the sequence. I generally recommend something in the 24mm to 50mm range because it gives good quality without having to capture too many frames… but again, this decision needs to consider the subject we're trying to capture.
Manual White Balance
Using automatic white balance in a panoramic sequence can cause some problems as the camera may choose a different white balance setting in each image in a sequence - which can make the stitching process more difficult or lead to some visible issues in the final result. Sure, this can be fixed before stitching but I find it easier to use a manual white balance setting. I find that using one of the settings your camera has (like daylight) is effective but I recommend using a specific color temperature of 3800K.
Manual Exposure or Aperture Priority
In the daytime, I tend to like using aperture priority while at night, I prefer manual exposure. I find that giving the camera any more control than that can result in a change in depth-of-field which can cause problems in the stitching process and visible issues in the final result. Of course, manual exposure works well in the daytime too but I tend to like using aperture priority in a lot of cases and this seems to work well.
When you shoot from a position that's not level, it can result in a scene that's either bowed or arced in a distorted curve. This is possible to fix but it can lead to some distortion and loss of overall quality and in some cases, loss of content - especially near the corners. To minimize this bowing and arcing effect, I recommend making sure your camera is shooting from a level position. To do this, I like using some type of panoramic leveling tool with a bubble level as I have in the Acratech GP Ballhead but this feature is available in a variety of other heads as well. Either way, it's ideal to shoot from a level position as it helps to minimize the curved horizon effect that is often seen without it.
Of course, this may not always be possible as I'm sometimes shooting at an upward angle (especially in night photography) and in this case, I recommend making sure that your tripod is level as the next best alternative. To do this, you would ideally be able to use a bubble level on your tripod as this works well for the purpose. As an alternative, I'll share another approach that one of our workshop students (Dr. John Bickel) suggested - where you straighten out the head of your tripod and then pick it up by the head. Then adjust the length of each leg so they each touch the ground at the same time. This approach works fairly well in a pinch when you don't have a bubble level and the ground itself isn't level.
This type of distortion (also referred to as Nodal Point Distortion) comes from shooting fairly close subjects when the camera is rotated around a point other than the nodal point of the lens. Often times, architectural photographers will see this problem when they're shooting slanted roof lines that show a different perspective because the camera is being rotated at the camera body rather than the lens. There are special types of panoramic heads and nodal slides that directly address this issue and they're very effective at mitigating the problem.
That said, this extra gear may not be necessary depending on the types of subjects you typically shoot. If you're shooting far away subjects like mountains and other terrain, I don't think it's necessary. If you like to include trees and other subjects fairly close (50 feet or less) however, this may well help. When this problem appears, you'll most often see the problem in objects that don't appear lined up or as a straight line in places where the stitching occurs.
Avoid Delays Between Shots
One common mistake that I see people make is to include some delays between some of the images in a sequence which can lead to changes in the scene. As you might imagine, the scene may change a bit from the time you shoot your first image to the last - especially when shooting 20-30 second exposures at night. So it's really important to shoot and rotate, shoot and rotate without wasting time between each shot.
Avoiding delays is made easier when you're prepared to rotate consistently without any significant waiting. If you have too much time between shots, clouds and/or movement of the stars can make stitching the scene more difficult.
Shooting Changing Content
If your subject looks like it has any chance of changing during your shooting, make sure to shoot the portion that has the highest chance of changing first. Whether this be a cloud or a moon or whatever, you'll want to make sure to catch it when it's good. And if you shoot it last, it may not look like you planned by the time you get to it - so shoot it first.
Overlapping Each Frame
I typically recommend between 40% and 50% overlap for each frame in a panoramic sequence and to make the math easier, I often use 50%. I do this because I want to give the panoramic stitching software plenty of content to find in common so it can match up each frame in the sequence with ease. It really goes a long way in helping the stitching software be successful in stitching on the first try without having to resort to more advanced and more expensive stitching software.
So how do I get the right amount of overlap? There are a variety of approaches but perhaps the most precise one is to use the degree markings commonly found on a panoramic head. And to determine the amount of rotation needed, I'm going to point you toward a chart published by B&H Photo that identifies the field-of-view for common lenses. Just determine the field-of-view for the lens you're using, cut that in half, and that's how many degrees you'll need to rotate between shots in a panoramic sequence.
As an alternative, I've often used a less precise approach where I find a recognizable feature on the far right side (or left, depending on which way I'm rotating) and then after the shot, I'll rotate until that feature is in the middle. I identify this feature with either the optical viewfinder or in image review after shooting a frame and then move it to the middle by using either the optical viewfinder or just by looking over the top of the lens.
Avoid Underexposed Areas
This can be an especially big challenge when shooting at night. Without proper illumination of your foreground, stitching software will struggle to find common content which can lead to difficulty in successfully stitching a panoramic sequence together. I typically use either moonlight or light painting to help minimize this issue. When light painting, I find I have the best success with a wide stationary light (like an LED light panel) as it helps to make sure that the illumination is consistent with each frame. If your light painting isn't consistent, the results can be just as difficult to stitch together as an underexposed foreground.
Overshoot The Corners
As panoramic sequences often result in some arcing or bowing of the horizon, we often find ourselves needing to correct that distortion in post-processing. Of course, I recommend taking steps to minimize this in shooting, but it still happens. Adobe Lightroom and Bridge have a feature called boundary warp that can help to address this issue but the result can still lead to some loss of content or quality - especially near the corners. So in shooting, I recommend shooting beyond the areas you want to include so you can make sure to include them after any cropping is needed. Besides the possible loss of content, this approach also helps to get the best quality possible as the center of your images tend to have better quality than the corners.
Portrait Or Landscape and Multiple Rows Or Up & Down
Traditionally, photographers shoot horizontal panoramas using one or more horizontal rows with a camera shooting in a portrait orientation. I find that shooting in a vertical (portrait) orientation tends to help in getting a result that's tall enough and in overshooting the corners which leads to improved image quality.
That said, I've seen another approach used at night that's worth mentioning as it's effective in helping the stitching software figure what to do with images that include just the sky and no foreground which can be especially challenging with multiple rows of images captured at night. So instead of shooting multiple horizontal rows, this approach involves shooting with the camera in a horizontal (landscape) orientation with multiple vertical columns.
To explain further, I would shoot one horizontal shot in the lower left, then shoot again above that, and again above that. Then I'd move to the right a bit and shoot the bottom, again in the middle, and again in the top before repeating each column until I get to the right side. The approach may sound strange but it seems to help in successfully stitching a panoramic sequence captured at night - especially when there some of the images with just sky and no foreground.
Panoramic Stitching Software
While this article is focused more on the shooting side of panoramas, I thought I'd share my favorite stitching software as well. Generally, I prefer to use either Adobe Lightroom or Adobe Bridge to handle my stitching as they seem to handle my stitching needs well and they maintain high quality with a raw file as the result. At this time, Adobe Photoshop is not as good and is therefore not recommended. I'll also mention that PTGui has been a long time favorite of mine as well even if I don't use it as much now that Lightroom and Bridge are so good at panoramic stitching. In cases where either of these fail to stitch a sequence, PTGui is a great alternative as it allows me to manually add control points which can be a life-saver when needed.