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underwater photography

Dec - 1 - 2012
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Underwater photography is one of the most challenging of all photographic activities. In addition to the technicalities of producing a proficient image, the camera must be kept dry and the photographer must ensure his or her survival in an alien environment. Underwater photography is for some enthusiasts merely a means of recording marine life encountered, but for others it can become a passion, and diving only the means of transport to the underwater studio. Whichever level is aspired to, underwater photography can appear to be a daunting challenge; but with a logical approach to equipment and techniques respectable results can be achieved very quickly.

History

Notwithstanding the problems involved, attempts to take photographs underwater began as early as the middle of the 19th century. In 1856 William Thompson obtained a murky picture of damage to a bridge on the Wey estuary in southern England, about 6 m (20 ft) below the surface. In subsequent decades further efforts were made on both sides of the Atlantic, including an experiment by Eadweard Muybridge in San Francisco Bay in 1875. Contemporary advances in engineering, e.g. bridge building; the development of submersible vehicles; and, perhaps above all, the laying of submarine cables, created a demand for reliable ways of recording objects underwater. (A century later, the offshore oil boom would give a comparable stimulus.) But the earliest sustained progress was achieved by Louis Boutan in the 1890s. Between 1893 and 1899, using a succession of cameras and both natural and artificial lighting, he captured some remarkable images off the Mediterranean coast. In 1899 he obtained clear photographs of underwater vegetation at night, and of a plaque at a depth of 50 m (164 ft), using battery-powered arc lamps in watertight housings. Although Boutan’s interests shifted elsewhere, his book, La Photographie sous-marine (1900), and the projection of some of his pictures at the 1900 Paris Exhibition, encouraged further experiments. By 1920, in addition to developments in underwater cinematography, still cameras were being used for a range of applications, from salvage work to the Allied investigation of mines flooded and booby-trapped by the German army. In 1926 the American ichthyologist W. H. Longley and the National Geographic photographer Charles Martin took underwater autochromes in the Caribbean, publishing them in the magazine in January 1927.

In the 1930s, 1940s, and 1950s important developments took place in three main areas: exploration of the deep oceans; the invention of aqualung equipment that vastly increased the mobility of divers and photographers at depths down to c.40 m (130 ft); and the creation of stroboscopic lighting systems. A key figure was Jacques-Yves Cousteau (1910–97), whose books and films kindled public awareness of the underwater environment. He had a long association with Harold Edgerton, who contributed cameras, lighting equipment, and sonar positioning apparatus for expeditions to locations as diverse as the Mediterranean and Lake Titicaca in the Andes. (In 1976 Edgerton took part in a vain attempt to locate the Loch Ness monster; in 1986, an Edgerton–Benthos camera took some of the first still photographs of the rediscoveredTitanic.) Cousteau also collaborated with the Belgian Jean de Wouters in developing an underwater 35 mm camera, the Calypsophot, the design for which was bought by Nippon Kogaku and launched in 1963 as the Nikonos.

In the late 20th century, ever-improving equipment, oil exploration, and the growing popularity of leisure diving strongly encouraged underwater photography by both amateurs and professionals. Notable among many outstanding practitioners was Leni Riefenstahl, who learned diving in her seventies and produced two books of tropical underwater photographs, Korallengärten (Coral Gardens; 1978) and Wunder unter Wasser(Underwater Miracle; 1990).

Equipment

Today’s would-be underwater photographer must first choose a camera system. This can range from spending a few pounds on a disposable camera for depths of 3–5 m (10–15 ft), or investing £1,000 or more in a housing for an autofocus SLR system. Between these options are amphibious semi-compact systems produced by Nikon (the Nikonos—though production ceased in 2001) and Sea & Sea (the Motormarine), which offer various lens options for total flexibility. As these cameras do not have reflex viewing, camera-to-subject distance must be estimated and the lens focused accordingly. However, framers and prods can be used to measure subject distance in close-up or macro work, when using accessory lenses and extension tubes; and wide-angle lenses have the advantage of considerable depth of field. SLR systems are bulkier and heavier, but considerably more flexible, offering both a wide choice of lenses and autofocus. From the turn of the 21st century a growing range of underwater digital equipment became available.

Most underwater photographs are lit at least partly by artificial light. This is both to ensure adequate exposure in the sometimes gloomy depths (allowing the use of smaller apertures), and to restore colours largely absorbed by water as distance from the surface increases. Amphibious flashguns are available for either compact cameras or housed SLRs which are compatible with the camera’s TTL flash exposure control. A housed camera may be combined with an appropriate (housed) dedicated flashgun to ensure total exposure control and compatibility with matrix metering systems. Amphibious flashguns are available in a variety of power options and with differing beam angles: lower power, narrow beam for close-up and macro, and high power, wide beam for wide-angle photography. Finally, a flexible or jointed arm is needed to attach the flash to the camera system and allow changes of lighting position and angle, dependent on the subject.

To produce successful underwater photographs it is essential to appreciate the physical constraints that working underwater imposes.

Colour Absorption

White light or daylight is made up of several colours ranging from the warm end of the spectrum (reds and oranges) to the cool end (blue and green), and water is an efficient filter of light (Fig. 1). It is more efficient at the warm end of the spectrum, and noticeably soaks up red light by a depth of c.10 m (30 ft). Absorption intensifies with increasing depth until very little colour remains. The human brain is able to compensate in part for this colour loss and allow continued recognition of the suppressed colours even if they are less vivid. Colour film, however, is balanced for use in daylight only and cannot compensate; it therefore records only what it ‘sees’. This rule applies not only to increasing depth but also to distance. So, even in only a few feet of water, too great a distance from the subject will result in loss of colour by absorption. To overcome this, the photographer must get as close to the subject as possible; stay shallow if shooting with natural light; or use a flashgun to restore the lost colours. Colour-correcting filters can be used in shallow water, but as these also affect exposure values, flash is the most efficient choice.

Reflection and scatter

Even in a flat calm up to 25 per cent of the sun’s light is reflected by the water’s surface and this figure increases as conditions become rougher and waves present a variety of angles to reflect the light. Light underwater is also scattered by particles of matter suspended in it. Even the clearest tropical water contains countless minute suspended particles that reflect light from their own surfaces and degrade definition of the image as subject distance increases. An above-surface subject photographed on a misty day would lack definition. Owing to suspended matter these conditions exist permanently underwater, so that the photographer must approach as near to the subject as possible, using a wide-angle or close-up lens to minimize the scatter effect.

Refraction

Light rays are refracted (bent) as they pass from the water through the face-plate of the diver’s mask or the flat port of the camera; this has the effect of magnifying what is in vision by about 25 per cent, thus making an object appear to be both larger and closer (Fig. 2a). The magnification also reduces the angle of view that the lens has on land (i.e. there will be less in the picture under water); and with wide-angle lenses refraction will also cause a variety of optical distortions at the edge of the picture. With longer focal length lenses this can be an advantage, particularly when using close-up and macro lenses, as magnification is enhanced. However, wide-angle lenses must be corrected for underwater use by means of a dome port, which restores the correct angle of view and removes the optical distortions (though not the magnification) (Figs 2b and c).

Backscatter

This term refers to reflection of light from the particles suspended in the water between camera and subject (Fig. 3). If the flashgun is positioned close to the camera lens and pointed straight at the subject, much of the light will be reflected back at the lens by these particles, producing a ‘snowstorm’ effect in the final image. The remedy is to position the flashgun above the subject and at an oblique angle, approximately 45 degrees, thus ensuring that any backscatter from the particles is directed at the flash and not the lens. When pointing the flashgun, the photographer must also be aware of the effects of refraction, particularly when working at a distance from the subject. It is important not to aim at the ‘apparent distance’ of the subject, which appears to be closer than it actually is, but about 50 per cent beyond it.

‘O’ rings

Cameras, whether amphibious or housed, require ‘O’ rings as a seal to keep the water out. Part of general camera maintenance and dive preparation is the cleaning and lubrication of the ‘O’ rings in the camera, housing, and flash body. It is often assumed that more silicone grease on the ‘O’ ring will produce a better seal, but this will attract more dirt and debris; the ‘O’ ring should only be lubricated lightly until it shines. As some manufacturers now use silicone-based ‘O’ rings which require more regular greasing to prevent them drying out and shrinking, it is essential to check in the instruction manual whether the material used is silicone or neoprene rubber. When equipment is left unused for long periods the main ‘O’ rings should be removed and stored in plastic bags to prevent them becoming deformed by long-term compression.

Safety

For any dive, safety must be the prime consideration, and it is important to have a reasonable level of experience and proficiency before taking the plunge. Just as in land photography, improving results will come with patience and attention to detail, and perfecting each technique before moving on to the next.

Fig. 1 Colour absorption and reflection
Fig. 1. Colour absorption and reflection.

Fig. 2a Refraction
Fig. 2a. Refraction makes it difficult to aim the flash correctly.

Fig. 2b Flat port underwater
Fig. 2b. Flat port underwater. When light rays pass from one medium to another, in this case from air to water, rays are refracted or bent. As a result objects appear to be about 25% bigger and closer, and the angle of view of the lens is decreased by approximately the same percentage.

Fig. 2c Dome port underwater
Fig. 2c. Dome port underwater. A dome port corrects refraction and maintains the angle of view of the lens.

Fig. 3 Backscatter
Fig. 3. Backscatter. By keeping the flash above the lens and aiming it at the subject at 45° backscatter (light reflected from suspended particles) will be minimized.

Mark Webster

Cousteau, J.-Y., The Silent World (1953).

Howes, C., Images Below (1996).

Webster, M., Art and Technique of Underwater Photography (1998).

Edge, M., The Underwater Photographer (1999).

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