Four Projections of an Ultra-wide Image
de Sales Church, Philadelphia, 120 x 90 degrees. Photo by T K Sharpless, processed with
Hugin. Click images for larger views.
An 11mm ultra-wide
angle lens on a 35mm camera would give a picture like the rectilinear
view at upper left. It is easy
to see the distortion near the edges, if
you compare it to the cylindrical view (lower left) which shows things
at their natural angular widths.
The Pannini view (lower
right) seems to blend the rectilinear and cylindrical
projections. The edges are less stretched than in the
rectilinear view; the bowing of horizontal lines is less than in
the cylindrical view, though still objectionable to many eyes (van
Gogh, however, might have drawn it just this way). The
Panini-General projection can straighten the horizontals, giving
the image at upper
right. It covers the same angles as
the rectilinear image,
but looks as if it had been made with a longer
focal length lens. However, no real lens could have taken that picture.