All About Panoramic Photography
Panoramic photography is a technique of photography, using specialized equipment or software, that captures images with horizontally 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, like the familiar letterbox format in wide-screen video.
While there is no formal division between "wide-angle" and "panoramic" photography, "wide-angle" normally refers to a type of lens, but using this lens type does not necessarily make an image a panorama. An image made with an ultra wide-angle fisheye lens covering 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 it is high. 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.
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 would only classify as wide-angle, not panoramic.
The device of the panorama existed in painting, particularly in murals as early as 20 A.D. in those found in Pompeii, as a means of generating an immersive 'panoptic' experience of a vista, long before the advent of photography. In the century prior to the advent of photography, and from 1787, with the work of Robert Barker, it reached a pinnacle of development in which whole buildings were constructed to house 360° panoramas, and even incorporated lighting effects and moving elements. Indeed, the careers of one of the inventors of photography, Daguerre, began in the production of popular panoramas and dioramas.
The development of panoramic cameras was a logical extension of the nineteenth-century fad for the panorama. One of the first recorded patents for a panoramic camera was submitted by Joseph Punch berger 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, used curved plates and added the crucial feature of setgears 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.
After the advent of wet-plate collodion process, photographers would take anywhere from two 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 N. 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.
Following the invention of flexible film in 1888, panoramic photography was revolutionised. Dozens of cameras were marketed, many with brand names indicative of their era; such as the Cylindrograph survey camera (1884), Wonder Panoramic(1890), Pantascopic (1862) and Cyclo-Pan (1970).
View from the top of Lookout Mountain, Tennessee, Albumen prints, February, 1864, by George N. Barnard
Short rotation, rotating lens and swing lens cameras have a lens that rotates around the camera's rear nodal point and use a curved film plane. As the photograph is taken, the lens pivots around its nodal point while a slit exposes a vertical strip of film that is aligned with the axis of the lens. The exposure usually takes a fraction of a second. 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 occupy between 1.5 and 3 times as much space on the negative as the standard 24 mm x 36 mm 35 mm frame.
Cameras of this type include the Widelux,Noblex, and the Horizon. These have a negative size of approximately 24x58 mm. The Russian "Spaceview FT-2", originally an artillery spotting camera, produced wider negatives, 12 exposures on a 36-exposure 35 mm film.
Short rotation cameras usually offer few shutter speeds and have poor focusing ability. Most models have a fixed focus lens, set to the hyperfocal distance of the maximum aperture of the lens, often at around 10 meters (30 ft). 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.
Rotating lens cameras produce distortion of straight lines. This looks unusual because the image, which was captured from a sweeping, curved perspective, is being viewed flat. To view the image correctly, the viewer would have to produce a sufficiently large print and curve it identically to the curve of the film plane. This distortion can be reduced by using a swing-lens camera with a standard 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].
Rotating panoramic cameras, also called slit scan or scanning cameras are capable of 360° or greater degree of rotation. A clockwork or motorized mechanism rotates the camera continuously and pulls the film through the camera, so the motion of the film matches that of the image movement across the image plane. Exposure is made through a narrow slit. The central part of the image field produces a very sharp picture that is consistent across the frame.
Digital rotating line cameras image a 360° panorama line by line. Digital cameras in this style are the Panoscan and Eyes can. Analogue cameras include the Cirkut (1905),Leme (1962), Hulcherama (1979), Globuscope(1981) and Roundshot (1988).
Fixed lens cameras, also called flat back, wide view or wide field, have fixed 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 cropped images in a panoramic aspect ratio using a small area of film. Advanced 35 mm or medium format fixed-lens panoramic cameras use the full height of the film and produce images with a greater image width than normal.
Pinhole cameras of a variety of constructions can be used to make panoramic images. A popular design is the 'oatmeal box', a vertical cylindrical container in which the pinhole is made in one side and the film or photographic paper is wrapped around the inside wall opposite, and extending almost right to the edge of, the pinhole. This generates an egg-shaped image with more than 180° view.
Because they expose the film in a single exposure, fixed lens cameras can be used with electronic flash, which would not work consistently with rotational panoramic cameras.
With a flat image plane, 90° is the widest field of view that can be captured in focus and without significant wide-angle distortion or vignetting. Lenses with an imaging angle approaching 120 degrees require a center filter to correct vignetting at the edges of the image. Lenses that capture angles of up to 180°, commonly known as fisheye lensesexhibit extreme geometrical distortion but typically display less brightness falloff thanrectilinear lenses.
With digital photography, the most common method for producing panoramas is to take a series of pictures and stitch them together. There are two main types: the cylindrical panorama used primarily in stills photography and the spherical panorama used for virtual-reality images.
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. Some digital cameras can do the stitching internally, either as a standard feature or by installing a smartphone app.
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 (panoramic mirror lenses) 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. The image, a reflection of the surface on the mirror, is in the form of a doughnut to which software is applied in order to create a flat panoramic picture, such software is normally supplied by the company who produces the system. 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. The Mirror lens system uses only a partial section of the digital camera's sensor and therefore some pixels are not used. Recommendations are always to use a camera with a high Pixel count in order to maximize the resolution of the final image.
There are even inexpensive add-on catadioptric lenses for smartphones, such as the GoPano micro and Kogeto Dot.
Some cameras offer 3D features that can be applied when taking panoramic photographs. The technology enables the camera to take shots from different angles and combine them, creating a multidimensional effect. Some cameras use two different lenses to achieve the 3D effect, while others use one. Cameras such as Samsung NX1000, and Sony Cyber-shot DSC-RX1 offer the 3D Panorama mode.
A panoramic photograph of the Camp Nou stadium,Barcelona in January 2011
Source: Wikipedia
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