National Geographic : 1960 Nov
The author and his motion-stopping camera WHEN Crawford H. Greenewalt ranges the hemisphere for hummingbird pictures, he pays two plane fares. The extra ticket loads 250 pounds of camera gear, which sometimes rides first-class while its owner goes tourist. Mr. Greenewalt's equipment is unique; nothing like it is commercially available. He and his associates perfected it in seven years and 100,000 miles of travel devoted to photographing hummingbirds. Ornithology and photography are hobbies; the presidency of E. I. du Pont de Nemours & Company occupies Mr. Greenewalt's working time. As a Life Trustee of the National Geo graphic Society, he helps guide The Society's educational and scientific activities. His study of birds began years ago when Mrs. Greenewalt placed a feeding station on a balcony of their home near Wilmington, Delaware, and the antics of the winged diners fascinated him. Deciding to film the balcony dramas, he fell prey to a challenge that led him to hummingbirds, those chesty flyweights whose elusive colors and blurred wingbeats frustrated old-time photographers. Proof of his success appears on these pages and in his notable new book, Hummingbirds (footnote, page 660). "The bulky gear you see below presents a problem," says the author. "With so much weight to carry, chasing hummingbirds is impossible; they must come to me. Two lures draw them into camera range: their own nest, or a feeder filled with sugar water. "No camera shutter can freeze a hummingbird's flight. Only an extremely short, bright flash of light will stop the wings' rapid motion. Standard equipment has a flash lasting about a thousandth of a second, allowing the bird to complete a twentieth of its entire wingbeat. The solution: a three-lamp, battery-powered unit that produces a flash last ing 30 millionths of a second. "The principal function of the camera shutter is to ex clude sunlight. Its action must be fast enough so that only the electronic flash registers on the film; too much daylight expo sure would blur the image. As for camera, many makes could be used, but I prefer a specially modified Hasselblad. "Birds rarely pose prettily in the center of the picture, and for that reason I prefer a film Icancrop.Iusea2'4 -inch square format, cropping the re sulting transparency to fit the standard 2-by-2 slides. "For adequate perspective at a reasonable working distance, I use a 135-millimeter lens, not a long telephoto. The birds in effect take their own pictures by flying through a beam of light shining on a photocell. "When the beam is inter rupted, an electrical impulse trips shutter and flash. Total reaction time: about a fortieth of a second. "If I tried to trip the shut ter manually, my slower reac tion time-more than a tenth of a second-would result in a view of departing tail feathers, or no bird at all." 664 KODACHROMEBY NATIONALGEOGRAPHICPHOTOGRAPHERJOHN E. FLETCHER© N.G.S.