Traditionally, panoramas would be taken using a fixed manual exposure, bracketed if needed. But panoramic software has advanced to the point that they can handle the assembly and blending of source images taken with wildly different exposures. I am making available a set of files taken in Ripon Cathedral that shows the ease at which high contrast scenes can be tackled without having to take large amounts of bracketed photos.
In this example, the base exposure throughout the scene varied by 6 stops (1/40th to 0.63s) hence there was a large amount of inter-frame contrast. But the contrast in any one frame (intra-frame) was just within the capabilities of my camera, hence I was able to take a 5+1+1 shooting pattern, without bracketing, and capture the scene without excessively blown highlights. This is variation of the usual 4+1+1 shooting pattern but with an extra shot that was taken aimed at the bright highlights of the sunlit windows.
This extra shot was masked into the rest of the pano and invoked for an “underexposed” export of the stitch in addition to the normally exposed export. Hugin has no problems in handling the differently exposed frames and after photometric optimisation, the frames blend seamlessly. The normal and underexposed versions were combined using Enfuse and minor edits performed.
Hopefully this example demonstrates that panoramic software tools have come a long way since the traditional advice of locking off exposure was formulated. With some practice, the use of autoexposure when taking panoramas can be quite effective in speeding up workflow and creating a more efficient workflow. Of course, judgement is still required to use where necessary bracketing in order to tame intra-frame (as opposed to inter-frame) contrast.
Download Example Files (from above) and extract to folder
Open Hugin and import source files
Set the lens parameters (Focal Length 8.7mm, Crop 1.5), Full Frame Fisheye for images taken around at 90 degree yaw intervals, Circular Fisheye for the Zenith and Nadir images. Assign lenses so that the the first 4 images are Lens 0, Zenith is Lens 1, Nadir is Lens 2.
Mask each image. For the first 4 images, mask off the tripod/panohead and any other extraneous objects, also the corners. Set crop circles for the Zenith and Nadir.
Now add control points to each overlapping pair of images. Concentrate on placing a good spread of points along the centre of the overlapping regions. There is no need for placing points away from the likely seam lines.
Add vertical control points/lines so that the pano will be level
Start optimising the position, gradually including field of view, barrel, then everything except translation. Periodically check for control points with large errors, correct if necessary. Use the Custom Optimisation options to fine tune the process.
Check that the geometry of the assembly is satisfactory using the Preview Window.
Start on optimising exposure. Choose Low Dynamic Range, then Custom. Deselect optimisation of Vignetting and Camera Response. Optimise just the exposure values, the the Red and Blue Multipliers.
Finally, stitch and export the panorama in your preferred format.
You try stitching the image using the automatic mode in Hugin, or in any other panoramic programme of your choice.