Panoramic photography
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Panoramic photography is a technique of photography, using specialised equipment or software, that captures images with elongated fields of view. It is sometimes known as wide format photography. The term has also been applied to a photograph that is cropped to a relatively wide aspect ratio. While there is no formal division between "wide-angle" and "panoramic" photography, "wide angle" normally refers to a type of lens, but this lens type does not necessarily image a panorama. An image made with an ultra wide angle fisheye lenscovering the normal film frame of 1:1.33 is not automatically considered to be a panorama. An image showing a field of view approximating, or greater than, that of the human eye - about 160° by 75° - may be termed panoramic. This generally means it has an aspect ratio of 2:1 or larger, the image being at least twice as wide as its height. The resulting images take the form of a wide strip. Some panoramic images have aspect ratios of 4:1 and sometimes 10:1, covering fields of view of up to 360 degrees. Both the aspect ratio and coverage of field are important factors in defining a true panoramic image. [citation needed]
Photo-finishers and manufacturers of Advanced Photo System (APS) cameras use the word "panoramic" to define any print format with a wide aspect ratio, not necessarily photos that encompass a large field of view. In fact, a typical APS camera in its panoramic mode, where its zoom lens is at its shortest focal length of around 24 mm, has a field of view of only 65°, which many photographers[who?] would only classify as wide angle, not panoramic.[citation needed]
History
One of the first recorded patents for a panoramic camera was submitted by Joseph Puchberger in Austria in 1843 for a hand-cranked, 150° field of view, 8-inch focal length camera that exposed a relatively large Daguerreotype, up to 24 inches (610 mm) long. A more successful and technically superior panoramic camera was assembled the next year by Friedrich von Martens in Germany in 1844. His camera, the Megaskop, added the crucial feature of set gears which offered a relatively steady panning speed. As a result, the camera properly exposed the photographic plate, avoiding unsteady speeds that can create an unevenness in exposure, called banding. Martens was employed by Lerebours, a photographer/publisher. It is also possible that Martens camera was perfected before Puchberger patented his camera. Because of the high cost of materials and the technical difficulty of properly exposing the plates, Daguerreotype panoramas, especially those pieced together from several plates (see below) are rare.[citation needed]
After the advent of wet-plate collodion process, photographers would take anywhere from 2 to a dozen of the ensuing albumen prints and piece them together to form a panoramic image (see: Segmented). This photographic process was technically easier and far less expensive than Daguerreotypes. Some of the most famous early panoramas were assembled this way by George Barnard, a photographer for the Union Army in the American Civil War in the 1860s. His work provided vast overviews of fortifications and terrain, much valued by engineers, generals, and artists alike. (see Photography and photographers of the American Civil War)[citation needed]
Following the invention of flexible film in 1888, panoramic photography was revolutionised. Dozens of cameras were marketed, many with brand names heavily indicative of their time. Cameras such as the Cylindrograph, Wonder Panoramic, Pantascopic and Cyclo-Pan, are some examples of panoramic cameras.[citation needed]
Panoramic cameras and methods
Short rotation (or swing-lens)
Short rotation is a term used to define cameras that have a lens that rotates around the camera's rear nodal point (the optical point from which the focal length is measured) opposite a curved film plane.[1] As the photograph is taken, the lens pivots around its nodal point while a slit exposes the vertical strip of film that is aligned with the axis of the lens. The entire exposure usually takes a fraction of a second and the camera's functions similarly to the method of viewing a scene by turning one's head from side to side on a steady level. It is also referred to as rotating lens or swing lens. Typically, these cameras capture a field of view between 110° to 140° and an aspect ratio of 2:1 to 4:1. The images produced commonly take up 1.5 to 3 times as much space on the negative as the exposure made by traditional 35 mm cameras.
Notable cameras of this type include the Widelux, Noblex, and the Horizon They have a negative size of approximately 24x58 mm. The more obscure Russian "Spaceview FT-2", originally an artillery spotting camera, produced even wider negatives, 12 exposures on a 36-exposure 35 mm film.
Short rotation cameras have a number of limitations. They usually offer relatively few shutter speeds and have poor focusing ability, with most models having a fixed focus, set to the hyperfocal distance of the maximum aperture of the lens, often at 10 meters (30 ft) or more.
Thus, panoramic photographers wishing to photograph closer subjects must use a small aperture to bring the foreground into focus, limiting the camera's use in low-light situations. For these reasons, cameras of this type are most often used outside, specifically for landscape or kite photography, where there is usually plenty of available light and there is less requirement for short focusing depths.
Rotating lens cameras also produce a notable and odd distortion of straight lines. If the horizon, for instance, is placed even slightly off-center, the horizon line will bow slightly in the opposite direction. This 'distortion' looks unusual to the viewer because the image, which was originally viewed and captured from a sweeping, curved perspective, is being viewed flat. To view the resulting image correctly, the viewer would have to produce a sufficiently large print and curve it identically to the curve of the film plane in the camera. This type of 'distortion' can be reduced by using a swing-lens camera with a 'normal' focal length lens [the FT-2 has a 50 mm while most other 35 mm swing lens cameras use a wide-angle lens, often 28 mm], and by photographing buildings from a corner location, not from the center of a flat surface.[citation needed]
Swing lens panoramic cameras have also been built --in small to very large sizes-- for use while suspended by kites [or helicopters, in the modern era].[citation needed]
Full rotation
Rotating panoramic cameras (also referred to as slit scan or scanning cameras) are similar to swing-lens or short rotation cameras, but are capable of 360° of rotation or more. The whole camera rotates. A clockwork or motorized mechanism rotates the camera continuously and evenly and simultaneously pulls the film through the camera so the motion of the film matches the motion of the image movement across the image plane. Exposure is made through a narrow slit. Using the central part of the image field produces a very sharp picture that is consistent across the frame. These cameras are widely used for group pictures, particularly of athletic teams. Digital rotating line cameras image a 360° panorama line by line. A linear sensor has 10,000 sensor elements that use charge-coupled device technology. A 360° panorama is composed of approximately 120,000 individual `line images'. For this example, the final image has approximately 1,200 million pixels. Digital rotating line cameras are used for documenting historic buildings or sites. [citation needed]
Notable digital cameras in this style are the Panoscan and Eyescan. Analogue cameras include the Cirkut, Hulcherama, Leme, Roundshot and Globuscope, all of which are capable of 360° of rotation.[citation needed]
Panoramic photography is commonly used in theatre to photograph the entire cast. Traditionally, the cast will have a "runner" who will appear on both sides of the photograph by running to the other after the camera has moved past them. [citation needed]
Fixed lens
Fixed lens cameras, also called flatback and wide view or "wide field", are panoramic cameras that have fixed, stationary lenses and a flat image plane. These are the most common form of panoramic camera and range from inexpensive APS cameras to sophisticated 6x17 cm and 6x24 cm medium format cameras. Panoramic cameras using sheet film are available in formats up to 10x24 inches. APS or 35 mm cameras produce images in a panoramic aspect ratio using a small area of film, thereby losing a significant portion of the film area. Advanced 35 mm or medium format fixed-lens panoramic cameras use the full height of the film and have an increased image width, producing high resolution images.[citation needed]
Because these cameras expose the film in a single 'instantaneous' exposure like traditional cameras, fixed lens cameras can make use of a flash, which would not work consistently with rotational panoramic cameras because the flash, which usually are around 1/1000 of a second, would only be captured on the part of the image that is being exposed when the flash fires. These cameras do not cause linear objects to curve, making them the panoramic camera of choice for architectural photography.[citation needed]
With a flat image plane, 90° is the widest field of view that can be captured with normal sharpness and without significant wide-angle distortion or light fall off by a traditional lens and camera using a single, flat piece of film. Lenses with an imaging angle of up to 120 degrees require a center filter to correct for light fall off toward the edge of the image. Lenses that capture angles of up to 180°, commonly known as fisheye lenses, exhibit extreme geometrical distortion but typically less brightness falloff at the edges than normal (rectilinear) lenses.[citation needed]
Notable cameras of this type are the 35 mm Hasselblad X-Pan, the medium format Linhof 612PC, Horseman SW612, Linhof Technorama 617, Tomiyama Art Panorama 617 and 624, and Fuji G617 and GX617.
A company named ImmerVision has created the new panomorph lens. This lens provides a full hemispheric field of view with no blind zone, different from catadioptric lenses that cause a blind spot in the middle of the image. [citation needed]
Segmented
Segmented panoramas, also called stitched panoramas, are made by joining multiple photographs with slightly overlapping fields of view to create a panoramic image. Stitching software is used to combine multiple images. In order to correctly stitch images together without parallax error, the camera must be rotated about the center of its entrance pupil.[1] [2] [3]
Catadioptric cameras
Lens and mirror based (catadioptric) cameras consist of lenses and curved mirrors that reflect a 360 degree field of view into the lens' optics. The mirror shape and lens used are specifically chosen and arranged so that the camera maintains a single viewpoint. The single viewpoint means the complete panorama is effectively imaged or viewed from a single point in space. One can simply warp the acquired image into a cylindrical or spherical panorama. Even perspective views of smaller fields of view can be accurately computed.
The biggest advantage of catadioptric systems is that because one uses mirrors to bend the light rays instead of lenses (like fish eye), the image has almost no chromatic aberrations or distortions. Because the complete panorama is imaged at once, dynamic scenes can be captured without problems. Panoramic video can be captured and has found applications in robotics and journalism.[citation needed]
References
- ^ a b Littlefield, Rik (2006-02-06). "Theory of the "No-Parallax" Point in Panorama Photography" (pdf). ver. 1.0. Retrieved 2007-01-14.
{{cite journal}}: Cite journal requires|journal=(help) - ^ Kerr, Douglas A. (2005). "The Proper Pivot Point for Panoramic Photography" (PDF). The Pumpkin. Retrieved 2007-01-14.
- ^ van Walree, Paul. "Misconceptions in photographic optics". Retrieved 2007-01-14. Item #6.
- Meers, Nick (2003). The World of Panoramic Photography. Rotovision. ISBN 2-88046-692-X.
- Johnson, R. Barry (2008). Correctly making panoramic imagery and the meaning of optical center. SPIE Proc. Vol. 7060.
See also
External links
- Panoramic/360° photography techniques and styles at Curlie
- Panoramic image galleries at Curlie
- Catadioptric Imaging at Columbia University
- Panoramic Association A worldwide organization devoted to educating the public on and showcasing the work of panoramic photographers.
- A timeline of panoramic cameras 1843-1994
- Gigapan panoramic image system: hardware, software and web-based image sharing community
