One of the first steps I teach when we work on panoramas at a workshop is that you need to put your camera in manual to ensure that you get an even exposure from one side to the other. Setting that exposure requires panning across the scene and choosing a setting that is a good compromise from the lightest to darkest areas. Obviously this requires soft and even light and makes it difficult to photograph panoramas where part of the scene is brightly lit and part is in shadow.
Hacking on the merged image later using somewhat crude tools like the Shadow/Highlight adjustment in Photoshop is the most common workaround to try to address the problem of unevenly lit panoramas. But thanks to some goading by my friend Jim Ludemann I’ve started experimenting with using HDR when shooting tricky panoramas to allow me to create successful images even of scenes which have difficult lighting conditions. In this post we’ll take you through the process, step by step…
Quick Tips for Shooting a Traditional Panorama
To recap for those who are new to panoramas or need a refresher, the first key is to level your tripod and camera (a leveling base or tripod head with a level on it are really helpful to get a level base, then either a level on your camera or Nikon’s virtual horizon help you level your camera). Second, if you have a panorama rail/plate use it to move your camera back so that the lens’s nodal point is over the axis of rotation (if you don’t have one don’t panic, you’ll just need to rely on Photoshop to help clear up the distortion). Third, find a good exposure that works reasonably for the entire scene and set your camera to manual on that exposure. Finally, take a series of evenly distributed photos across the scene, overlapping each one by about 50%. I shoot a frame with 1 finger held up to mark the start of the sequence and two fingers to end just so I remember the series is a panorama and don’t delete individual frames while I’m editing. That’s all there is to getting started!
When to Consider an HDR Panorama
Finding the correct exposure for a panorama means checking via a spot meter or careful sweeping of the scene with an automatic metering mode turned on and looking for a combination of shutter speed and aperture (f-stop) that will give you enough depth of field and will provide detail in both the highlights and the shadows.
A very common problem is in scenes where a portion is lit and a portion is in shade. That problem is made worse if the lit portion includes the sky. It is almost impossible to get a lit sky and a shadowed ground area both properly exposed in the same frame without a neutral density filter—which limits you to a simple “line” between light and shadow.
In the above image of the beautiful pink sandstone Bantay Srei temple near Siem Reap in Cambodia from our Southeast Asia Photo Safari I had to pick a “bright” enough exposure to show the shaded stone of the temple—the primary subject of my image. But that exposure blows out all the detail in the sky so it looks like it is a dull dirty white and detracts from the image.
This was a clear opportunity to use HDR (high-dynamic range) techniques to capture both the blue and white detail in the sky and the color of the walls without creating all the noise and artifacts that any attempt to post-process them in Photoshop would cause.
In this image you can see the full scene (complete with our safari participants practicing their panorama technique off on the right) shot with bracketed exposures of +1 and –1 in addition to my original exposure setting and then processed using HDR. Now we have the detail in both the temple itself and in the sky which has really come to life.
We can further tweak the HDR image in Photoshop by cropping it to match our original image and bringing out the pink color of the walls using a quick adjustment in the Lab color space. The resulting image looks like we had a soft even light across the entire scene—despite the tall trees and outer wall of the temple off to the right which make it very difficult to get the temple fully lit before late morning when the light is harsh.
How to use HDR with your Panoramas Step by Step
The only change you need to make from your shooting workflow is to capture a bracketed series of images instead of single images as you move across the scene. To make this image I simply set my Nikon D700 to bracket a 1 e.v. so it captured images “spot on” and – 1 e.v. and +1 e.v. (in this case at 1/15th second at f/16, then at 1/30s and at 1/8s—all at ISO 560).
Next, when I got to my computer I used the Auto-stack feature of DigitalPro to group the images together for easy processing (there is a downloadable script for Photoshop which will also do this) and then did a trial run with one of the bracketed sets of images in Photomatix Pro to see what settings looked best. In this case I chose a version of their “Smooth Skies” preset and then saved out the settings to a file I could re-use. Then I used the batch capability of Photomatix Pro to process all the images using my saved settings.
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Now I had a nicely balanced set of “developed” images in TIFF format I could simply open as a batch into Photoshop. Photoshop’s own File->Automate->Photomerge did the rest. I turned on Vignette Correction and Geometric Distortion Correction and left the perspective on Auto. Photoshop merged all the images into a good looking a seamless composite.
From there I ran my standard “raw input” script which does automated noise reduction using Noise Ninja and a simple raw pre-sharpening with nik Sharpener Pro. The final step was using a Lab curve (made much simpler with Mike Russell’s great plug-in Curvemeister) to bring out the reddish hues in the pink sandstone and the green of the forest trees.
Once you get the hang of it HDR panoramas are really only a little bit more work than the traditional kind and they can bring a whole new dimension to many otherwise difficult to capture scenes. We hope you get a chance to give them a try!—David