Session T-11: Tropical photography - extension

Time: 4 PM - 5 PM

Goals:

· To provide information regarding camera care in a tropical environment
· To suggest alternative ways to photograph subjects in the tropics
· To provide technical transfer and workshop skills to the trainee presenting the session

Overview:

This session is presented as a special project by a trainee. The need to document work is important, especially when dealing in technical areas. The opportunity for the PCV in the field to record workshops and/ or special projects is only limited by expertise as a photographer. In the tropics, there are special considerations that must be adhered to; it is these "rules" that this presentation of tropical photography deals with.

Procedures:

Materials and Equipment:

· Flip chart, pens, misc. cameras and camera equipment

References:

· Eastman Kodak Co. Rochester, N.Y. 14560 Notes on Tropical Photography, 1978
· Photographing Tidepools, Velma Bosworth, Oregon State University Sea Grant, 1978

Notes on Tropical Photography

Suggestions for Residents:

The instructions in the following sections are intended for photographers who work in tropical climates either as residents or on location for a considerable time. The precautions may or may not be necessary, depending on the particular climate and on the facilities available. Today, many buildings in the tropics are air-conditioned, and such appliances as humidifiers, dehumidifiers, and refrigerators-portable or otherwise- are either available locally or they can be shipped in and used where there is a supply of electricity.

Care of Photographic Equipment:

Moderately high temperature is not in itself detrimental to cameras and accessories, but intense heat should be avoided except for those times when the equipment is in actual use. When high temperatures is coupled with high humidity, the growth of fungus on bellows, camera cases, fabrics and even lenses is a certainty.

Do not leave cameras and accessories either in hot sunshine for longer than is necessary or in enclosed spaces, such as the glove compartment or the trunk of a car that is standing in the sun. Remember that a white surface reflects heat as well as light. For this reason, a white-painted enclosure remains cooler in sunshine than a dark-colored one.

Abrasive dust is a major problem in many tropical climates. There are few enclosures that can exclude it altogether. Enclosing the camera and auxiliary lenses in plastic bags is helpful, but in a humid atmosphere the stagnant air in the bag promotes the rapid growth of fungus. Equipment should not be kept enclosed in this way for longer than a few hours.

Constant cleaning of the camera parts before and after use is a necessary procedure. Special care must be taken with lenses; the abrasive action of gritty dust is a serious threat to the glass surfaces, and consequently, to the photographic image. Clean lenses by gently brushing or blowing off dust. Any wiping or cleaning with fluid or tissue must be done with the greatest care and as infrequently as possible. Keep both ends of lenses capped when not in use.

Some photographers mount a haze filter or a piece of optical glass permanently on the lens as protection against abrasion by dust. A scratched filter can be renewed at moderate cost if necessary. A Haze filter has no appreciable effect on exposures.

Storage of Photographic Materials:

Sensitized photographic materials are perishable products under practically any conditions. Proper storage is therefore important at all times, especially in tropical climates, because deterioration is rapid in a hot and humid atmosphere.

Black-and-white materials withstand moderate heat without serious changes in their characteristics. Color films intended for amateur use (sometimes called "consumer" films) should be stored where the temperature will not rise above 24°C (75°F) for more than a few days. Kodak color films intended for professional use (they have the word "professional" in the film name) should always be stored in a refrigerator at 13°C (55°F) or lower.

Extremes of relative humidity are a serious threat to all photographic materials, even at moderate temperatures. At high temperatures, the effects of humidity are greatly accelerated. Not only are the sensitometric characteristics of the material impaired, but physical damage occurs as well. Sheets of film may stick together or become glazed in patches where they touch one another. Rolls of film may "block" or stock so that they cannot be unwound, or the outside edges of the roll may be affected more than the inside so that the film buckles. Moreover, cardboard cartons swell and break open, labels drop off, and cans rust. These effects can be expected if the relative humidity remains above 60 percent. Extremely low relative humidity, on the other hand, is not quite so serious, but if it falls below 15 percent for a considerable time, an electric humidifier should be installed and set to maintain a relative humidity of 40 to 50 percent in the storage area.

Storage of Films and Color Papers: These materials are supplied in packages incorporating a barrier to protect them against moisture vapor. Only when the relative humidity is above 60 percent for most of the time is it necessary to protect the packages against dampness. Black-and-white films and papers can be stored at normal room temperatures in an air-conditioned room, for example Professional color materials should be stored in a refrigerator until the seal is broken.

When the seal has been broken, films should be used as soon as possible. Since the air in a refrigerator is moist, partially used packages should be returned to the refrigerator in a sealed can together with a desiccant to absorb the moisture within the container. When partially used packages of color paper are stored in a refrigerator, press out excess air from the foil envelope, make a double fold at the open end, and seal with adhesive tape.

In general, do not keep more film and paper than necessary in stock, particularly when good storage conditions are not available. Photographic materials are also affected by chemical activity of fumes and gases. These include some plastic formulations, paints, lacquers, exhaust from internal combustion engines, and sulfide toning solutions. In a hot atmosphere, the solvents in paints, lacquers, etc, evaporate and permeate the air in an enclosed space much more rapidly than they do at normal temperatures. Consequently, do not store papers and films in newly painted rooms or cabinets, and keep the materials as far away as possible from the kind of containment mentioned above.

Storage of Black-and-White Photographic Paper: Although Kodak black-and-white papers are very stable materials, their photographic and physical properties deteriorate when they are stored for considerable periods under conditions of high temperature and high relative humidity.

Ideally, black-and-white paper should be stored at temperatures between 5 and 10°C (41 and 50°F). However, paper intended for use within a few months can be kept in an air-conditioned room at normal temperature. Unlike films and color papers, black-and-white papers are not sealed against moisture; they should, therefore, be kept in a place where the relative humidity is not too high. Remember that in a hot and humid climate, the relative humidity will be even higher in a basement or other place where the temperature is lower than that of surrounding areas. A refrigeration dehumidifier installed in the storeroom will help keep the humidity within acceptable limits. If the relative humidity is below 25 percent most of the time, photographic paper will dry out and become brittle and difficult to handle in use. Then an electric humidifier should be installed and set to maintain a relative humidity of about 45 percent.

As a general rule, do not stock more paper than you expect to use within a few months. However, if large stocks of paper must be maintained, it would probably be economical to provide the best possible storage conditions. A conditioned room or chamber in which the temperature and the relative humidity can be controlled is ideal.

Warm-up Times:

When films are taken from cold storage or from an air-conditioned room into a warmer atmosphere, allow sufficient warm-up time before opening the heat-sealed envelope or other moisture barrier. Otherwise, moisture condensation forms on the surfaces if the film temperature is below the dewpoint of the surrounding air.

Care of Exposed Films:

When a film has been removed from the moisture-resistant package, it is immediately subject to deterioration in a hot and humid climate.

When the film has been exposed, the latent image will also deteriorate. Color films are particularly susceptible in this respect. Consequently, all films should be processed as soon as possible after exposure. If processing facilities are not available in your vicinity, mail the film to the most convenient processing station immediately. If you are unable to do this for some reason, enclose the films in an airtight jar or can together with a desiccant and place them in a refrigerator. Exposed films can be kept for several days in this way.

Exposure:

Although it has often been said that less exposure is needed in the tropics as a general rule, this is not necessarily so. Measurements made in various parts of the world have shown that when atmospheric conditions are similar and when the sun is at the same elevation in the sky, the intensity of illumination is practically the same regardless of geographical location. Since the sun reaches a higher elevation in the tropics than elsewhere, the light intensity is extremely high when the sun is at its zenith. This in itself is not a difficulty--exposure can easily be adjusted for the higher light intensity. However, when the atmosphere is clear and the sky cloudless, the lighting contrast is also extremely high. In these conditions, shadows tend to lack detail even though the highlights are correctly exposed or perhaps overexposed.

With nearby subjects, fill-in flash is helfpul and the only remedy available for color pictures other than waiting for more favorable lighting conditions. In black-and-white work, you can give extra exposure to get more shadow detail and then reduce the development of the film to lower the highlight density. Another effect of taking photographs when the sun is directly overhead occurs in landscapes without high trees or buildings. The absence of shadow then yields a very flat, uninteresting picture. The only way to avoid this result is to photograph the subject either earlier or later in the day when shadows are longer.

Preservation of Negatives:

Because deterioration caused by residual chemicals in the emulsion takes place rapidly in a hot and humid atmosphere, always fix and wash films thoroughly. In handling negatives, wear Kodak Cotton Gloves to avoid finger marks. When the negatives are not in actual use, keep them in clean envelopes, because any greasy residue deposited on the surfaces by indoor atmosphere promotes the rapid growth of fungus, which eventually destroys the gelatin coatings on the film.

The most important consideration in storing negatives in a humid climate is to keep them dry. That is to say, maintain a relative humidity between 40 and 50 percent in the storage area. If a building is properly air-conditioned, the relative humidity will not be higher than this.

However, if it exceeds 55 percent for any considerable period, install an electric dehumidifier. If other means of keeping negatives dry are not available, they can be stored in a heated cabinet. Alternatively, they can be enclosed in a metal box with a desiccant.

For the best storage conditions, negative envelopes should conform to American National Standard Requirements for Photographic Filing Enclosures for Storing Processed Photographic Films, Plates, and Papers ANSI PH4.20-1958 (R1970). In a tropical climate, however, negatives should not be stored for a long time without inspecting their condition. Do this at regular intervals so that any deterioration that might have taken place can be remedied and more suitable storage conditions arranged.

Preservation of Prints:

In general, the same remarks apply to preserving prints as to preserving negatives. Careful processing and storage in a dry place are the principal requirements.

When black-and-white prints are used for decoration or display, hypo alum toning has been found helpful in preserving the prints from atmospheric effects and from attack by fungus. Color prints should be lacquered so that they can be wiped clean occasionally.

Prints should always be dry-mounted--many pastes and gums are hygroscopic, and they attract insects and fungus. Use photography-quality mounting board-impurities in ordinary cardboards may discolor the prints in a short time. This applies also to interleaving paper and album leaves.

At relative humidities below 60 percent, prints keep well in an album if the pages are large enough to allow a 3 1/2 inch border on all four sides of the prints. The closed album then gives a measure of protection against atmospheric effects and attack by insects or fungus, particularly when the prints have been treated with a fungicide such as Hyamine 1622.

If the relative humidity is above 60 percent, pack the prints or the album in a sealed container together with a desiccant. Single prints, whether mounted or unmounted, should be interleaved with good-quality paper. To be sure that-deterioration is not taking place, inspect valuable material periodically and renew the interleaving paper or any other packing material at these times.

Fungus:

Airborn spores of fungus are everywhere, and they exist in immense variety. Mold and mildew are the familiar kinds that fourish in warm, damp places. Generally, the type of fungus troublesome to photographers in the tropics grows most readily at temperatures between 24 and 29°C (75 and 84°F). It feeds on dead organic matter such as leather, cloth, wood, paper, and gelatin, but it will spread and damage other materials-the glass of lenses in cameras and binoculars, for example.

Moisture is essential to the growth of practically all varieties of fungus, and they thrive in darkness. Obviously, in a hot damp atmosphere, cameras, sensitized materials, negatives, and prints, as well as clothing and other fabrics, will be attacked. The only really practical way to prevent the attack of fungus is to keep the articles dry and clean as far as this is possible.

A heated box or a cabinet in which an electric light bulb or a small electric heater element is kept switched on can be used to keep cameras and other equipment dry. Adjust the temperature in this type of enclosure so that it is about 5.5°C (10°F) higher than the room temperature. Also, allow air to circulate through ventilation holes in the top and bottom of the box or cabinet. Do not keep films or photographic papers in enclosures such as that described above.

The best way to reduce the relative humidity in a room is by using a refrigeration-type dehumidifier. The room must, of course, be resistant to the passage of moisture through walls, ceiling, and floor, and it must be kept closed. Then the heated enclosure described above is not necessary. In this connection, remember that although a room-type air conditioner reduces the temperature, in doing so it may increase the relative humidity. Some units are more efficient in dissipating moisture than others. In a properly air-conditioned building, however, the difficulty will not arise.

Notes on Tropical Photography Kodak Publication No. C-24