Learning Center
Using Telephoto

Michael Campbell is no stranger to the stars. The British-born commercial and portrait photographer who now resides in San Diego has created photographic portraits for Dr. Jonas Salk, England’s Princess Anne, and former British prime minister Sir Anthony Eden.

But it was a different type of star-gazing that led Campbell to capture some lunar luminescence recently with the Tamron 200-500mm lens. “I’ve tried several Tamron lenses in the past, and I wanted to compare the Tamron 200-500mm with the Sigma 50-500mm and the 170-500 lenses,” says Campbell, who also uses the 200-500 in his fashion, sports, wildlife, and landscape photography. “The Tamron was the best of the lot. I took some shots of the moon right from my apartment balcony. I really didn’t have a reason to photograph it—it was just kind of an interesting way to test out the lens.”

One of Campbell’s artistic specialties, which has garnered him numerous awards and recognition in the photographic community, is his ability to lend a painterly effect to otherwise straightforward photographic portraits. Toward that end, he was able to incorporate his recent experimental moon shots into some of his other commercial captures. “Normally I’ll use the moon in a composition as a background object, like in some of the belly-dancer images I’ve done,” he explains. “You can even add the moon to a night or dusk shot. Most people shoot landscapes that include the sun or the moon already there. With digital imaging, however, I can take a night shot without the moon in it, add it in as a Photoshop layer, and place and size it wherever it looks good.”

His astronomical imagery acumen is no surprise when you consider the scientific background he boasts in addition to his photographic expertise. “I’m an ‘imageologist,’” he explains. “That term also spells out ‘I’m a geologist.’ You see, I have a masters degree in geology, and I also studied astrophysics, zoology, chemistry, physics, and math.”

Galaxy Quest
Craving a little cosmos capture of your own? Before you even attempt an evening of astrophotography, Campbell suggests finding the right locale and biding your time for the ideal night. “I used to drive up to Mount Palomar [an astronomical observatory near Pasadena, California], where you can get very clear skies with little interference from city lights,” Campbell says. “With a really long lens and a tripod to avoid camera shake, the detail in your picture will be limited by how much air is between your camera and the moon, and how clean this air is. Humidity, dust, and density fluctuations all degrade the quality of your image, reducing contrast and sharpness.”

Campbell advises getting out of town and heading to the mountains, the countryside, or the desert (“most people in Los Angeles have never seen any stars”) and choosing a night where moisture isn’t a factor. “Humid nights, even without visible mist, are worse than dry ones,” he says.

Once you’ve scouted out the perfect night and location, it’s time to start assembling your shooting setup. Campbell mainly shoots with his Fuji Finepix S2 or S3 on a tripod and with a cable release to minimize camera shake (he lost his own telescope when it was destroyed in the 2003 San Diego wildfires). And while the 200-500mm served him well for his own impromptu moon montage, more-serious night owls should consider even longer lenses. “I would use a longer fixed focal length to shoot the moon or the sun—you really need 1,500mm with a digital camera or 2,500mm for a film camera to get a full-size image,” he explains.

“If I were using a telescope as well, I’d use, say, an 8-inch telescope to photograph Saturn with a sidereal tracking system,” Campbell adds. For those who want to “piggyback” their camera onto a telescope, he offers the following suggestions:

Prime focus method (the simplest method for lunar photography): If you own a catadioptic telescope (e.g., a Schmidt-Cassegrain), remove the camera lens. Using a simple adapter like a T-ring (available at camera stores and astronomical supply houses), attach the camera directly to the telescope without its eyepiece. The telescope becomes the camera lens—in effect, a very long telephoto lens. A 5-inch Schmidt-Cassegrain telescope, for example, can become a 1,250mm, F/10 telephoto lens.

Afocal method: You’ll need two tripods for this setup: one for the camera, and one for the telescope. The camera (with your lens) is set up as close to the telescope eyepiece as possible and focused on the image seen through the camera.

Projection method (a more advanced method): This technique requires the use of a special adaptor that’s much more expensive than the simple T-ring used in the prime focus method, according to Campbell. The adaptor connects the camera without its lens to the eyepiece of the telescope.

Illuminating the Moon
When it comes to shedding some light on Earth’s most famous satellite, the assumption is often made that, because the moon is illuminated by the sun, a normal daylight exposure that follows the “sunny 16” rule (F/16 at 1/ISO film speed) will be correct. “Unfortunately, things aren’t quite that simple,” says Campbell. “The sun is indeed a constant light source, but the moon’s reflectance varies with its phase, and the amount of light absorbed by the earth’s atmosphere varies with the moon’s altitude above the horizon. Viewed from Earth, the luminance of the moon is far from constant.”

The reflectance of a full moon is approximately 15% (a light gray), but it’s only about 8% one day before or after the full moon, and it decreases to about 2% for a quarter moon, according to Campbell. Plus, many published lunar exposure tables work for astrophotography, but not necessarily for landscape photography. “Astronomers like to photograph the moon when it’s high in the sky, but landscape photographers prefer to photograph it near the horizon,” he explains. “The closer the moon to the horizon, the greater the absorption of light by the earth’s atmosphere—just as with sunlight. This absorption is less at higher elevations, and also varies with local atmospheric conditions, such as temperature and haze. The safest rule, when in doubt, is to bracket.”

As the focal length of your lens increases, the light captured by the lens is focused over a larger area of the film, according to Campbell. This requires that the exposure time increase as the focal length increases. Just don’t expose for too long, warns Campbell. “Because of the earth’s rotation, the moon appears to move approximately half its diameter in one minute, so long exposures are best avoided,” he says. “The longest acceptable exposure time is somewhat arbitrary, and depends on the amount of enlargement. For a 35mm camera, a 50mm lens is considered normal, so with a 100mm lens, the longest acceptable exposure time would be 2.5 to 5 seconds. With a 500mm lens, the time would be 0.5 to 1 second.” Campbell uses manual focus (“though at 500mm the moon may be large enough that you can use autofocus”) and focuses on Infinity for his celestial captures.

Solar-Powered Shooting
A solar eclipse is one of the biggest events in the astronomical community—and a photographic opportunity that can’t be beat. Use long lenses (400–800mm) if you're attempting a sun-only shot, he advises. “The sun is small (1/2 degree), so unless you use long lenses, your frame won't be satisfactorily filled. If your lens is too long, and you make long exposures for maximum corona, you won't be able to capture the full solar corona in the frame.”

To get a full 35mm negative of partial phases will require a much larger lens or a small telescope: “To fill the negative, a focal length of 2,000mm is recommended—and you must always use filters, like Mylar filter on the front of the lens, when photographing a partial eclipse,” Campbell adds.

If you’re shooting film, Campbell suggests using a low ISO type, like ISO50 or ISO100. “With an ISO100 film and filtered lens, a starting point for your exposure is 1/1,000 of a second at f/11—and this is just a starting exposure!” he says. “Your results will depend on the amount of filtration you are using. The best way to test your exposure is to go out and photograph the sun a few days before the eclipse with your filter system in place, develop the film, and see your results. You’ll have a much better idea of what your final results will be that way.”

Using black-and-white or color film can be left to your discretion. “An eclipse is almost completely a black-and-white event, and if you're interested only in ‘deep corona’ shots, black-and-white film might be the right choice,” he says. “But there are enough exceptions that I can also recommend color film. The only source of color close to the sun, for instance, are solar prominences, which are red.”

Perhaps one of the most critical factors when documenting this blazing beacon is making sure your focus is as exact as possible. “A bad focus causes uncertainties in determining the sun's radius and errors in measuring the position of the planet,” explains Campbell.

However, simply peering into your viewfinder and thinking you have good focus is no guarantee of a well-focused picture, according to Campbell. “The edge of the sun, possible sunspots, and perhaps Venus itself will offer you your best focusing opportunity,” he says. “Using a magnifier for the viewfinder may facilitate the focusing, but because of the magnifier’s own focus, it must be tested in advance.”

May the planets align for your next session with the stars!

Preparing for a Meteor Shower
You’ve checked your local astronomy club’s calendar for the next slew of meteor showers in your area. What’s the best way to ensure you successfully document these fast-moving streaks of light? “Find a hill with little light from the city, set the camera on a tripod, open up your shutter, and have a little hope!” says Campbell. “You should generally stop the lens down one stop when you shoot, because there's nothing like bright point sources to reveal spherical aberrations, chromatic aberrations, and all those other dirty words. Exceptions can be made if you have a very high-quality lens, if your target only fills the very center of the frame, or if you’re shooting a very faint object and can't afford to block half of the photons that pass through the front of the lens.” If you’re shooting film, use 200–400 ISO and bracket your exposures.