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Nikon Owner Issue 20

Stretching the Limits - Choosing the right equipment for panoramic photography by Michael Eleftheriades, AA Dipl.

The Origins

As with many optical inventions and optical toys, we can trace the origins of panoramic photography to the Victorian era. The invention is credited to Robert Barker (1739-1806) an Irish painter who also patented the name 'panorama' - a Greek word meaning 'all encompassing vision'.

Stretching the Limits by Michael Eleftheriades

At the time panoramas were painted on the inside wall of specially-constructed circular theatres. The fee-paying public would climb up the central staircase to an observation balcony, from where the 360-degree panorama could be viewed. Because the panoramic image boundaries went beyond the extremities of the balcony and its canopy, a quite dramatic illusion was created. This revolutionary concept was a huge success in London and in other large cities from 1787 onwards, and heralded the arrival of the cinema as the entertainment medium for the masses.

From examples that still survive today, we know that many of the earliest photographers, from 1880 onwards, experimented with panoramic photography. Panoramas depict the devastation caused by the San Francisco earthquake of 1906, and are composed of between 3-5 overlapping images, with the seams clearly visible. Some of the earliest local examples include panoramic views of the Thames and Piccadilly Circus from 1909. My first recollection of a panoramic camera was when we had to be photographed for the obligatory end-of-year school photograph. All 500+ students and staff would be seated in a semi-circle, in the centre of which the camera would rotate in a 160-degree arc, with the inevitable jokers managing to appear at both ends!

With the ubiquity of film, it wasn't long before specialised 'panoramic' cameras were invented. Many panoramic cameras remain in production today; from the inexpensive Lomo Fisheye, the affordable Horizon 202, the Widepan 617 and Pro II, to the professional Hasselblad XPan II, Fuji GX617 and Linhof Technorama cameras. Although the above can expose a larger film area than their contemporaries, there are few 360-degree film cameras. Some of the 'true' panoramic 35mm cameras are manufactured by the Swiss Roundshot company, and are capable of describing a 360-degree revolution while exposing the film, in less than a second! Incidentally, both the Roundshot 28-220 and Super 220 VR cameras use Nikkor lenses.

The Digital Domain

By the early 1990's the inexorable progress of digital had began. In 1991 Apple introduced QuickTime (the first digital media architecture available for a personal computer) and HyperCard (the first multimedia authoring environment). It wasn't long before a student on a summer internment, realised the idea of 'navigable scenes'. These were a type of digital movie which could be interactively controlled, and the potential of which was demonstrated soon after in The Virtual Museum (1992). This breakthrough demonstration was an inspiration to myself, as it provided not only a three-dimensional navigable environment, but the exhibits themselves were interactive scenes.

Stretching the Limits by Michael Eleftheriades

The full potential of this technology was realised in 1995 when Apple formally introduced QuickTime Virtual Reality (QTVR) which provided a set of API's (Application Programming Interfaces) for the display of virtual reality panoramas by all Macintosh applications. Alongside, the QTVR Authoring Suite was released, to enable the creation of panoramas. The methodology introduced relied on the capture of a sequence of images, taken with a 15mm or 24mm Nikkor lens, with a 50% overlap, which required 12 (30-degree interval) or 15 (24-degree interval) shots respectively to cover the 360-degree circle.

Stretching the Limits by Michael Eleftheriades

The image overlap is an essential requirement, as it helps in the analysis of image correlation, which determines the exact 'warping' parameters so that the image can register with the next. By applying a type of graduated mask (equivalent to a Photoshop layer mask) this overlap also helps to blend the images together, so that the seams are no longer visible. The result of this process is a panoramic image, which by default is 'warped'. However, when the same image is

viewed using the QuickTime Player, the reverse transformation is applied, so the image appears corrected, thus creating the illusion of viewing the real space through a viewing frame.

At the time, most photographers, including myself, were shooting on film. Results were excellent, but there were a few problems: film and processing are expensive, and scanning the many images resulting from a panoramic shoot was time-consuming and complicated. The biggest issue with film however was that if one or more of the images were incorrectly exposed, they would render the whole panorama unusable.

Stretching the Limits by Michael Eleftheriades

With the launch of the Nikon Coolpix 900 cameras in 1998 (and later on the greatly improved 950 and 990 models) and their corresponding wide-angle and fisheye converters, many VR photographers jumped at the opportunity, as most of the above problems were negated. Acquisition was quicker; because it was possible to view the results in the field, the scanning step was eliminated, and despite a lower resolution than film, one benefited from the cumulative effect of capturing many images. Although the Coolpix cameras remain popular today, their popularity with VR photographers has waned, not because of any inherent problems with the design, but because of the advent of the affordable digital SLR, and the quality and lens choice benefits afforded by Nikon's venerable interchangeable lens mount.

Lens Nodal Point

For a successful panoramic shoot, the images need to stitch as accurately as possible. For this to be possible, we have to rely on a remarkable optical principle: that the lens rotates around its 'nodal point', or more accurately, the 'centre of perspective' of the lens. It is worth noting that every lens has a different nodal point and this tends to vary in zoom lenses. There is a small change also when focusing, but in wide-angle and fisheye lenses it is negligible.

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