The Importance of Focusing
Johnny Horne of the Fayetteville Observer-Times captured this magnificent image of the 'diamond ring' during the total solar eclipse of February 26, 1998. A Sky & Telescope contributing photographer, Horne observed the event from the deck of Holland America Line's Statendam.
Don't let poor focus ruin your eclipse photographs. This is especially important when using telescopes and long telephoto lenses that do not have a fixed infinity setting. Most 35-mm cameras have optional magnifiers for the viewfinder, which aid with focusing. Once you achieve optimum focus, place a piece of adhesive tape across your lens's focus ring or telescope's focus knob to prevent it from accidentally being moved during the eclipse. The same technique also applies when setting zoom lenses, which can slip without warning, especially when aimed high in the sky.
For full-disk photography of the Sun, focus on the solar limb when the is image framed the way you want it don't move the limb to the center of the field for focusing. Schmidt-Cassegrain telescopes in particular have curved focal planes that make the edge focus a little differently than the center. Be sure to recheck your focus as the eclipse progresses, since changing temperature can cause the focus to shift slightly.
Mobility is often essential for successfully observing a solar eclipse, especially when the weather prospects are poor. Cruise ships have the advantage of being able to maneuver to dodge clouds on eclipse day. Sky & Telescope associate editor Edwin Aguirre took this snapshot of the MS Veendam’s crowded foredeck during the February 1998 eclipse in the Caribbean Sea.
Whether you're traveling by land, sea, or air to your observing site, try to keep your mount as portable, light, and easy to assemble and operate as possible. Portability is especially essential if you need to relocate in a hurry to escape clouds.
If the Sun’s altitude will be high during the eclipse, make sure your camera tripod can be aimed this high. A pan head with slow-motion controls offers smooth guiding when you are manually tracking the Sun, which moves at about ¼° per minute across the sky.
To improve a tripod's stability, hang a jug of water or a duffel bag filled with sand under the center post. You can also wrap plastic bags of sand on each leg or set the tripod on rubberized footpads to dampen vibrations. The mirror slap in single-lens reflex (SLR) cameras can cause blurred images, especially in long exposures on slow film. To further minimize vibrations, work the shutter button with a long cable release. Lock the viewfinder mirror up beforehand if possible. Last, choose your site so it's shielded from direct breeze; erect a windbreak if needed.
Use Film or Go Digital?
Japanese astro imager Shigemi Numazawa melds conventional photography with digital technology to obtain this highly detailed portrait of the February 1998 eclipse from Aruba. Numazawa made a series of exposures from 1/60 to 4 seconds long on Fujichrome Velvia 50 film with a Pentax 4-inch f/7 refractor and 2x teleconverter yielding an effective focal length of 1,400 mm at f/14. Using a technique he calls 'multiple-layer digital processing,' he digitized and composited nine exposures with Adobe Photoshop to produce this final image.
Selecting the best film for eclipse photography has never been easy, especially with the bewildering assortment of emulsions available today (Sky & Telescope:
January 1999, page 143). In general, however, color-negative emulsions (those used for prints) offer greater exposure latitude; that is, they record features over a wider range of brightness with a single exposure than transparency (slide) films do. On the other hand, slides render rich, vibrant colors that are not vulnerable to variations that occur when one makes prints from negatives.
When choosing the film's speed (ISO rating) bear in mind that the faster the film, the shorter the exposure. Short exposures tend to minimize blurring due to vibrations, rolling of the ship (if you're at sea), and tracking errors. But fast films tend to be grainier than their slower counterparts.
There is nothing worse than running out of film in the middle of totality. During an eclipse of 2 minutes or longer, it's easy to use up a 36-exposure roll, especially if your camera has a motor drive. And nobody wants to waste precious seconds fumbling in the dark to change films! The best advice is to load a fresh roll in the minutes just before totality begins. Pace yourself and keep track of the number of exposures made. It's the quality that counts, not the quantity. It's better to have a few perfect corona shots than three dozen poor ones.
The Digital Alternative
Sky & Telescope senior editor Dennis di Cicco used a Nikon Coolpix 990 digital camera and a Meade ETX70 refractor to acquire this image of totality on June 21, 2001.
The current trend in still photography is toward digital cameras, which use a CCD chip instead of film for capturing images. A digital camera's resolution is often measured by the number of pixels in its image. The more pixels, the higher-resolution the image will be.
Digital cameras range from entry-level point-and-shoots costing $200 or so to studio cameras costing from $3,000 upward. The newest category on the mass market (near the middle of this price range) are digital SLR cameras, which look and feel like 35-mm SLRs and have detachable lenses.
Digital cameras typically use removable memory cards to store images. High-resolution pictures require more memory, so eclipse imagers must plan ahead in order not to run out of memory at a critical time.