Using Fisheye Lenses for Architectural Photography Helmut Dersch (der@fh-furtwangen.de) Technical University Furtwangen The following example demonstrates the use of fisheye lenses to create wide angle perspectively corrected images. The distortion of the fisheye lens is corrected using my Photoshop/Gimp plug-in Panorama Tools. Together with software shift and tilt correction all requirements for architectural photography are met. With the much larger field of view of fisheye lenses, previously impossible effects can be realized.

The example image below is shot using the Sigma 15mm full-frame fisheye lens (Olympus OM1). Angular coverage in the horizontal direction exceeds 140°, far more than what is achievable with rectilinear lenses. Also, please note the negligible light fall-off at the corners, which in rectilinear lenses often requires the use of center filters.

No tripod was used, and the camera was tilted upwards to get the whole view of the building (Concert Hall Freiburg). Also, a slight rotational missalignment is inevidable.

All these errors can be corrected in one step using Panorama Tools. The image is remapped to rectilinear projection, shifted vertically and horizontally, and slightly rotated. If required, the rgb-misalignment at the edges (one of the problems of ultra-wide lenses) could have been corrected also. The resulting image is shown below:

Step-by-step description:

You need a working installation of Panorama Tools.

Open the fisheye image
Select Panorama Tools and 'adjust'
Push 'prefs' and select options (b) and (c) (create new image), then push 'ok'
In 'adjust', select 'insert' and 'use options'
Push 'set' and fill the dialog as shown below.
Enter 'ok' twice. The Rectilinear image is created. You can cut the part you want to keep.

The three angles yaw/pitch/roll are used to shift/tilt and rotate the image. To determine suitable values, choose a somewhat smaller final image size (Panorama width and height = 500 pixels), and try some numbers until you like it. Then create a large final version.

If you need additional corrections, press 'correct'. A new dialog comes up, which allows you to correct rgb-misalignements,
additional radial and vertical distortions, skew, etc. If your lens exhibits light fall off at the edges, you can correct that separately using 'correct's Radial Luminance tool.