Photographing the Analemma : Most people say you have to be nuts to attempt a year-long exposure of the Sun. Those who have succeeded will probably agree.
The other night, in the twilight of consciousness that precedes sleep, I found myself attending the annual year-end meeting of a fictitious club. The membership secretary had just stepped to the podium, and his report went something like this:"Gentlemen," he began, there being no women present, "I am pleased to announce that in our two-decade history, 1999 was the best year ever. Membership swelled by more than 60 percent and currently includes individuals from England and the Ukraine as well as the United States.
"But," he continued, "with only five members, our club is still rather small. Furthermore, we remain disappointed that no women or individuals from the Southern Hemisphere have joined.
"However, there are no plans to amend our membership requirements. They are the same as always. Applicants must have a knowledge of astronomy and photography, and the perseverance -- some might say it's actually a lack of good judgment -- to attempt a year-long, multiexposure photograph using one camera and a single piece of film. The idea is to record the Sun's changing position in the sky as seen at the exact same time of day throughout the year. The resulting figure-8 pattern is known as the analemma. People who succeed are awarded immediate lifetime membership. There are no annual dues, since those were paid by the trials and tribulations that accompanied the making of the photograph."
Sleep brought an end to the meeting before those present got up to speak. In some ways this was fortunate since, as the club's charter member, resident historian, and notorious windbag, I would have droned on about the taking of the first analemma photograph. But it would have been interesting to hear about the recent success stories, and thus was born the idea for this article.
What Is the Analemma?
Except in Earth's artic regions, during June the Sun rises in the northeast and sets in the northwest. By December the compass points have swung to the southeast and southwest, respectively. The Sun's daily trek across the sky is high during summer months but low in the winter as seen from temperate latitudes. These changes are well known to everyone, whether by observational experience or from grade-school teachings. They result from Earth's axis of rotation being inclined about 23 11/42[degrees] to the plane of our planet's orbit, and they give the analemma its north-south dimension.
Far more subtle is an east-west shift of the Sun's position, which gives rise to the so-called equation of time familiar to anyone who studies the workings of sundials. In general, the Sun reaches an imaginary north-south line in the sky (the meridian) at local noon. But if we compare with a uniformly running clock the exact moment the Sun reaches the meridian, we find that there are days this happens early (sundials running "fast") and other days it happens late (sundials running "slow"). Some of this shift is also caused by the tilt of Earth's axis, a fact that surprises many people who have heard about the equation of time, since it is commonly believed to arise only from the eccentricity of Earth's orbit. Eccentricity does play a role and causes the figure-8 loops to be of unequal size and shape.
The analemma has been discussed several times in this magazine, most recently in the December 1988 issue, page 674. Although an ancient concept, the analemma maintains a present-day following, and there is even a Web site (www.analemma.com) devoted to explaining it.
While the idea of transforming the analemma's "concept" into reality via the magic of time-lapse photography is relatively straightforward, the actual process is fraught with difficulties. Some, such as finding a suitable location to mount a camera for a year and figuring out how to trip the shutter at the right time, are intuitive. Others, such as properly framing the scene, selecting suitable film, and creating a workable exposure schedule based on unpredictable weather, are less obvious at the outset.
In this magazine's June 1979 issue, page 536, I described taking the first analemma photograph as well as the failed one-year "test" exposure that preceded it. That article served as inspiration for England's H. J. P. Arnold, a skilled photographer, biographer of photography pioneer William Henry Fox Talbot, and author of Astrophotography: An Introduction in the Sky & Telescope Observer's Guides series. Between January 1988 and January 1989 Arnold made the second complete analemma photograph. He told his story in our June 1989 issue, page 678.
The third person to capture the analemma was Arizona-based outdoor photographer Frank Zullo, who was then living in the Phoenix area. His figure-8 pattern, completed in August 1991, was recorded on a single piece of film and later combined with foreground shots obtained at various locations. While never before shown in this magazine, the image has been widely published and most recently appeared in Hansen Planetarium's 1999 Wonders of the Universe wall calendar. Zullo is no stranger to Sky & Telescope readers, however. His article on a simple, hand-driven camera platform (S&T: October 1985, page 391) encouraged many people to build similar units in anticipation of photographing Comet Halley.
Following Zullo's success, things calmed down in the world of analemma photography until a remarkable turn of events late last year. In mid-September a small package containing Jack Fishburn's analemma shot arrived at our offices. A handwritten note accompanying the image offered the picture for use in our Gallery department. The unassuming note seemed more intent on playing up the accomplishments of Bell Labs, part of which is visible in the foreground, than touting the photograph as the achievement it certainly represents. Fishburn, who is an engineer at Bell Labs involved with the advance design of integrated circuits, had completed his image in August.
A half world away at the Ukraine's Crimean Astrophysical Observatory, Vasiliy Rumyantsev had also completed an analemma photograph in August. A professional astronomer doing asteroid research, Rumyantsev sent us a copy of his image by e-mail in mid-October. After nearly a decade of quiet, to have two successful analemma photographs completed in the same month is certainly noteworthy, especially since neither person was aware of the other's project.
Photographic Notes
Both analemma photographs finished in 1999 and the original made 20 years earlier were completed in situ -- the foreground shown is that over which the Sun's images were captured. Like Zullo's shot, the analemma photograph by Arnold is a composite that includes a more attractive foreground image than what was available from the camera's vantage during the Sun exposures.
Everyone except Zullo used color-negative film, since it has a greater exposure latitude than slide film and can better tolerate extended storage in a camera subjected to temperature extremes. Because Zullo's camera had to endure blistering heat that sometimes exceeded "110[degrees] Fahrenheit for days at a time," he made his Sun images on Kodak Plus-X black-and-white film, which is even more hardy that most color emulsions. Color was added to the Sun images during the compositing process. Each photographer tripped his exposures manually, except for my photographs, which used an electronic timer that required manual arming of the shutter anytime within 24 hours before the planned Sun exposure.
Everyone except Rumyantsev used cameras that were permanently fixed during the year. Because his viewing spot was unsheltered, Rumyantsev, with help from colleagues O. A. Blinov and V. S. Zhlobitsky, developed a novel mounting plate that allowed the camera to be removed and replaced without disturbing its aim. His site was outside as was that of Zullo, who mounted his camera under a patio with a wooden cover to protect it from direct sunlight and the elements between exposures. The other three photographers mounted their cameras behind windows, but Arnold opened the glass for each exposure.
Despite preparing exposure schedules in advance, everyone was at the mercy of the weather and ended up developing a game plan as the project progressed. Some tried to maintain a set interval between exposures regardless of delays caused by clouds. Others attempted to return to the planned schedule in spite of delays. The Sun's motion on the figure-8 pattern is far from uniform, and it moves very slowly at the time of the solstices, especially at the loop's small end (summer solstice in the Northern Hemisphere; winter solstice in the Southern Hemisphere). Because of this slow movement, Zullo increased the time between exposures near this solstice to keep the Sun images "aesthetically separated."
The only Sun image that most photographers considered crucial was at the figure-8's crossover point. The Sun is near this location only for a day or two around April 13th and again on August 30th each year.
Equipment ranged from a 4-by-5-inch plate camera for my image, to a medium-format Kiev-60 Flectogon used by Rumyantsev, to 35-millimeter cameras used by the other three photographers. Each was equipped with a wide-angle lens -- 90 mm for the plate camera, 50 mm for the Kiev-60, and 28 mm for the other three. All provided ample coverage for the complete figure-8 pattern, but each photographer expressed relief upon seeing the Sun remain in the field of view as the year wore on.
Everyone used some type of light-attenuating filter for the Sun and tested his exposures beforehand. The filters ranged from a weak, four-f/stop filter used by Rumyantsev to a dense Mylar filter used by Fishburn. Most chose to overexpose the Sun's image to compensate for days when either low altitude or thin clouds provided natural light attenuation.
Personal reaction to the individual attempts also varied. Zullo comments that during the project he found himself thinking, "I hope this comes out. I'm not about to try this again." Others remain somewhat noncommittal, but Rumyantsev writes, "I want to make several more analemma photographs in the years ahead."
Opportunities
Because the analemma traditionally has been shown in artwork as it would appear standing vertically on the meridian, the sloped views recorded in these photographs seem foreign to some people. Nevertheless, since Fishburn's image was taken in the afternoon, it's now easier to get a mental picture of how the pattern appears in different parts of the Northern Hemisphere sky. The opportunity still remains, however, for some enterprising photographer to record the analemma on the meridian. And what about capturing it from some location close to Earth's equator near the time of sunrise or sunset, when the pattern would lie parallel to the horizon? And, of course, there would be a shot from any place in the Southern Hemisphere, where the analemma's small loop appears nearer the horizon the way the larger loop does as seen from northern climates. Clearly there are still opportunities to join the club of analemma photographers with a membership application containing a unique view of the Sun's year-long path on the sky.
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| Author: | di Cicco, Dennis |
|---|---|
| Publication: | Sky & Telescope |
| Date: | Mar 1, 2000 |
| Words: | 1797 |
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