In recent decades field ornithology has progressed greatly and birding equipment has followed suit, although the basic equipment still consists of a pair of binoculars, a field guide, a notebook, and a pen or pencil (preferably a fine pen with waterproof black ink). The following items are what many of today's best birders use during their field work.

BINOCULARS
The cornerstone of birding equipment is a pair of binoculars. A good pair, if handled properly, can last a lifetime. Binoculars probably represent the single most expensive item in the beginning birder's field kit and should be the finest he or she can possibly afford. The two most important considerations in selecting binoculars are magnification and light-gathering ability. Most birders choose 7x, 8x, 9x, or 10x magnification; 10x binoculars might be difficult for some people to hold steady, but their strength makes them excellent for seeing pelagic birds, waterfowl, shorebirds, and birds of the forest canopy.

The light-gathering ability of binoculars is the amount of light that passes through the binoculars and enters the eye. This ability, reflected in the size of the "exit pupil," should usually be 4 mm or 5 mm; the larger the exit pupil the better. This number can be determined by dividing the diameter of the objective lens (the larger end of the binoculars) by the magnification. Thus 8x, 40 mm binoculars (otherwise known as an "8 by 40") has an exit pupil of 5 mm. In bright light the pupil of the human eye is closed by the iris to about 4 or 5 mm, but in dim light -- at dawn or dusk, on a dark day, in shadows, or in a forest -- it opens to about 7 mm. Thus binoculars that deliver an exit pupil of 7 mm (such as an 8x, 56 mm pair) flood the retina with light and produce a very bright image. Of course the optical qualities vary with the cost of the binoculars; the most expensive brands have the highest clarity and overall quality of image and the least distortion and discoloration.

The standard offset-prism binoculars have largely been superseded by newer straight-prism types. These tend to be more resistant to penetration by dust and water, in addition too having superior optical qualities and exterior coasting. Most straight-prism binoculars are available with rubber-armored casings that reduce the usual nicks and scratches and can often withstand a physical impact that can throw binoculars out of alignment. Some binoculars come from the factory pre-focused to about fifteen feet, but most do not; in this case, it is a good idea to have this adjustment made by the importer, if possible. There is an additional charge for this service, but it is well worth it. Binoculars with central-focusing wheels focus very fast and are the most practical, but they are not as well sealed against water and dirt and binoculars with individual eyepiece focusing.

Binoculars and other optical instruments should be carefully cleaned after each day's use, especially after exposure to dust, rain, or salt water. A cleaning kit consisting of lens tissues, liquid lens cleaner, and a soft brush should be carried along.

TELESCOPES
Sooner or later most serious birders find that they need increased magnification, especially for viewing waterfowl, shorebirds, and perched birds of prey. Most birders use a moderately priced telescope with a zoom-type eyepiece and magnification ranging from 20x to 45x, but other combinations are possible. If a single eyepiece is selected, a wide-angle 25x lens is the best choice for all-around birding. Recently, telescopes utilizing glass have appeared on the market. Such telescopes transmit light exceptionally well at low levels (dawn and dusk in particular), but are quite expensive. A lightweight, sturdy tripod that easily extends to eye level and has channeled legs with "flip locks" is the best support for a birder's telescope. Make certain that the extended legs remain spread apart when the tripod is lifted. If they do collapse toward the center when lifted, this may be corrected by simply adjusting a screw.

Much more costly are reflecting telescopes. They provide a superb image, but because the image is reversed, these telescopes take a little getting used to. Since you must look straight down into these telescopes, a short, very sturdy tripod is required. However, most birders find that once they have used these fine instruments, no other type can satisfy them. Some lower-priced reflecting telescopes are available; however, they are much inferior to more costly instruments.

FIELD GUIDES, NOTEBOOKS, and CHECKLISTS
Even expert birders do not disdain field guides and, although they may not carry the books into the field, they often keep their guides tucked away in the car. For those few experts who eschew the field guides -- and really for all birders -- a pocket notebook is a must. A notebook is essential for recording descriptions of rare or unfamiliar birds; behavioral and distributional observations; population data; journal or diary information regarding weather, vegetation, and companions; and even daily bird lists, although there exists a plethora of small field checklists for virtually all of the popular birding regions in the country. For economy of time in the field, some birders have switched to small, lightweight pocket tape recorders for note-taking; after the mini-tapes are transcribed into a journal at a more convenient time, they may be saved or re-used. Most experienced birders maintain an accurate journal that is faithfully kept up to date and may prove an invaluable source of recoverable data in the future.

TAPE RECORDERS AND MICROPHONES
Solid-state technology, miniaturization, and the improved quality of tape cassettes have allowed excellent, small, and relatively lightweight field tape recorders to replace the larger, heavier, reel-to-reel recorders. The finest of these small models can be modified to increase their frequency range to levels high enough to record almost any bird vocalization. If possible, they should have manual volume controls for maximum playback efficiency; automatic volume controls, found on most of these smaller models, do not serve as well since they cannot record a distant bird at levels higher than normal. The best-quality tapes should be used instead of bargain-priced tapes, and they should be no longer than ninety minutes in length. You can prevent accidental erasure by punching out one of the tabs on the top of the cassette.

The tape recorder is a versatile field tool, but it must not be abused by playing back calls and songs to lure sensitive species away from their nests or territories. Such recordings may even drive a less aggressive male from its territory. Tape recorders must be used with great care if your objective is to attract a species by a recording of its voice. A few brief snatches of voice will often do the job.

Recordings may be made as permanent records and as teaching devices for oneself and others. Field notes may also be recorded and transcribed later. The larger reel-to-reel recorders are still employed by professional wildlife sound specialists, since the quality of these machines can seldom be duplicated by the smaller recorders and their cassette tapes. This heavy, elaborate equipment, however, is not necessary for the simpler type of recording that most birders wish to do.

It is usually best to select a good microphone first and then find a suitable tape recorder, for even a modest, relatively inexpensive machine can do wonders with a fine microphone. The best types are those that capture the sound from a relatively small area so they can pinpoint the singing bird and exclude extraneous sounds. The finest unidirectional microphones are often quite expensive but are relatively small (compared with parabolic reflectors) and lightweight, and can be easily carried through the brush or forest, preferably in some sort of carrying case. Since most of the small recorders operate on AA or C batteries, spares should always be carried; alkaline batteries are more expensive, but their life expectancy is longer and fewer need be stocked. The record and playback heads of your tape recorder should be cleaned regularly with cotton swabs dipped in rubbing alcohol or with special demagnetizing cleaning tapes.

PHOTOGRAPHIC EQUIPMENT
A rather recent development in field birding has been the growing popularity of bird photography, using small motorized cameras equipped with small, lightweight, powerful telephoto lenses. This fairly compact outfit, coupled with fast films, can be easily carried into the field to record birding activities. This type of shooting has the advantage of capturing a trophy while allowing the game to live on. It is doubly satisfying because others are able to view the results and share in the pleasure. There is a more practical side to this type of "collecting." Rare or extralimital species no longer need to be collected for accurate verification, as many of North America's most unusual foreign vagrants have been recorded on film. Additionally, collections of photographs or movies can be assembled for instructional purposes; for informative and entertaining programs at birders' meetings and gatherings; for publication in journals, magazines, and books; or just for the personal pleasure of assembling a "life list" of bird photographs.

Simple photographic techniques are involved in birding, requiring minimal photographic equipment. Stalking the quarry on foot or by boat or auto until one is close enough to photograph it with a hand-held camera and telephoto lens is the most popular method, but it is usually employed only for the larger, tamer species. Portraits of smaller and more timid birds require more complex and time-consuming techniques and other equipment; such photography is not usually compatible with simple field birding.

The most basic equipment for bird photography by stalking consists of a lightweight, motorized, 35 mm, single-lens reflex camera equipped with a 500 mm or 600 mm reflex lens with a fixed diaphragm of about f:8 and high-speed color or black-and-white film. A slow lens (such as f:8) requires the focusing screen in the camera to be of the simple ground glass type and not the usual split-field range finder (which goes black and is unusable at apertures smaller than f:5.6). Some single-lens reflex cameras have interchangeable viewfinder screen capability. Unlike an automatic film-advance system, a true motor allows the photographer to shoot up to 4 frames a second, which is an advantage with a flying or fast-moving bird. The advantages of reflex lenses are that they are small, lightweight, close-focusing, and moderately priced. Their disadvantages are that they are slow, tend to have a "hot" spot in the center and darkening of the image at the corners, and are difficult to focus because of the darkened viewfinder. Out-of-focus highlights show up on the film as doughnuts or disturbing double images. Such a system can be hand-held, but some sort of shoulder brace or pistol grip/gunstock device will produce sharper photos. Commercial types are available, but anyone with a little ingenuity can build a suitable brace. While a monopod is useful, a tripod is awkward, especially if one is photographing in dense cover or on a pitching boat. Such a hand-held system requires a fast shutter speed, which should be about equal to the focal length of the lens. Thus a 500 mm lens requires a shutter speed of 1/500th second, and obviously a very fast film.

To obtain portrait-quality images of smaller birds one needs lenses of 400 mm, 500 mm, or 600 mm focal length. For example, to acquire a portrait-type image of a 6-inch bird with a 500 mm lens, the photographer must be within twelve feet of the bird, and this usually entails the use of a blind and electronic flashes placed near a location frequented by the birds, such as a feeder, nest, perch, or pool of water. Stalking small land birds is very difficult because they are shy and tend to remain in dense cover where light is dim. For this type of photography, conventional refracting lenses of long focal length (such as 400 mm, f:3.5 or f:4.5; 500 mm, f:4.5; or 600 mm, f:5.6) are required. These lenses are more expensive, larger, and heavier than the reflex lenses described above. The 400 mm and 500 mm lenses may be hand-held with a gunstock or shoulder brace, but the 600 mm lens requires a sturdy tripod. For close focusing with these lenses, an extension tube or bellows must be inserted between the camera body and the lens; this attachment eliminates infinity focusing until it is removed. Certain long telephoto lenses incorporate in a single unit the lens, extension bellows focusing mount, and pistol-grip/shoulder brace.

Some of the more expensive tele-extenders are quite good, increasing the effective focal length by a factor of 1.5x, 2x, or 3x, but the maximum lens aperture (speed) is reduced by a comparative factor. Thus a 500 mm, f:4.5 lens employed with a 2x tele-extender (or doubler) becomes a 1000 mm, f:8 lens and requires extremely rigid mounting on a sturdy tripod to ensure crisp pictures at the slower shutter speed dictated by the f:8 aperture. Such a combination would not be suitable for use with slower films and fast-moving birds.

Some more experienced bird photographers ultimately build their photographic equipment collection around the types of film they use. Faster films (with ASA ratings of 200 or 400) are notoriously grainy, but the faster film speed provides a greater latitude of shutter speed and lens aperture. Slower films (with ASA speeds of 25 or 64) are virtually grainless and excellent for reproduction in books and magazines, but the photographer must compensate for the slow film by using expensive, fast, long telephoto lenses, or intense electronic flash illumination, or both. Bird photography thus becomes a compromise between shutter speed and aperture, which ultimately depends upon the film speed, the intensity of the lighting used, and the maximum aperture of the telephoto lens. For example, if one chooses to use a film of speed ASA 64 with a 500 mm lens, then the lens must have an aperture of f:4.5 to be used in sunlight at 1/500th second, whereas an f:8 lens under the same circumstances could only be used at 1/125th second, making photography of flying birds impossible. Those photographers who choose to use slow color or black-and-white film are limited (with daylight) to expensive fast lenses. These conventional long telephoto lenses are equipped with iris diaphragms that can be adjusted to the shutter speed in use; the reflex lenses, however, have fixed apertures, so that the exposure is determined by the camera shutter. It is therefore best to choose a camera with an electronic shutter--providing essentially infinite shutter speeds within the ranges of the camera--for use with such fixed-aperture lenses.

ELECTRONIC FLASH
For stalking small birds in dense cover, it is essential to use electronic flash for illumination. A small 500 mm reflex lens can be employed with a 35 mm single-lens reflex camera mounted with a medium-size "telephoto" electronic flash. One problem is that many single-lens reflex cameras are synchronized for electronic flash at 1/125th second or slower. This is acceptable if there is not much daylight, since it is the flash and not the shutter that makes the exposure. However, if there is enough ambient light for an exposure by the shutter as well, a double or "ghost" image will result. Also, the single on-camera flash yields very stark, unnaturally harsh lighting not suitable for portraiture. The intense black shadows may make for an unsatisfactory portrait, but may be perfectly acceptable in a photograph meant merely to verify a record.

Most serious bird photographers eventually realize that good bird portrait photography and field birding are seldom compatible. Time and patience, coupled with knowledge of the subject and the right equipment, make for the superb photographs achieved by the experts. Professional results require more elaborate equipment: blinds; long, fast lenses; several electronic flashes and slave units; tripods, clamps, ladders, platforms; and slow, fine-grained films. Infinite patience is also necessary.

The most powerful electronic flashes require nickel-cadmium batteries, which are rechargeable, or 510-volt dry battery packs, which are not. These flashes produce great light; recycling of the capacitors is almost instantaneous, providing immediate and almost consecutive exposures. These larger units are not very portable and should be used at a feeder or from a blind. Photographic and observation blinds enable the photographer to remain hidden while close to the subject. They may be constructed of natural materials, assembled from rods and cloth for portability, or even purchased commercially.

Valuable photographic equipment must be cleaned, maintained, and carefully handled. Spares of essential items should be carried along. A camera should be insured; when it is not in use, it should be locked away out of sight in a car or truck. For maximum traveling security, cameras are best transported in waterproof, dustproof, and shockproof aluminum carrying cases. It is a good idea to disguise the camera case to avoid obvious invitations to thieves. Padded backpacks are very useful for transporting photographic equipment far into the field.

"OWL LIGHTS"
The location, observation, photography, and study of nocturnal birds requires powerful lights. Some units may be operated from a twelve-volt auto battery by way of special clamps to the battery terminals or, more conveniently, by way of the cigarette lighter. However, their usefulness is limited by the length of the power cord. Spelunkers' head lamps are best because they are powerful and leave the hands free. Six-volt "hunters' lamps" can be set on the ground and the light beam aimed at a bird. A standard, six-volt flashlight may be powerful enough, but it is least useful since it must be hand-held and aimed at the subject, leaving only one hand free.

Traditionally, beginners commence with the basic "kit" and incorporate more elaborate equipment, depending upon their interests. Within the broad framework of their hobby, many birders ultimately specialize, devoting much of their time to sound recordings, painting, bird photography, census-taking, life-listing, behavioral or distributional studies, writing, or a combination of these. Birding equipment may be as simple or complicated as a birder wishes, depending upon his aims and objectives.

Copyright 1996 Alfred A. Knopf. All rights reserved.