How to Photograph the Transit of Venus Safely
Paul Hyndman captured this stunning view of Venus crossing the face of the sun in hydrogen-alpha light on the morning of June 8, 2004 from Roxbury, Connecticut. He used an Astro-Physics 105-millimeter Traveler telescope fitted with a Coronado Solarmax90/T-Max and 30-mm blocking filter, a TeleVue 2X Powermate lens, and an SBIG STL-11000M CCD camera.
Andrew Cooper/W. M. Keck Observatory
March 13, 2013, marks 20 years since the W. M. Keck Observatory began taking observations of the cosmos. Located in arguably one of the most extreme and beautiful places on the planet -- atop Mauna Kea, Hawai'i, 13,803 ft (4,207 m) above sea level -- the twin Keck domes have observed everything from asteroids, planets, exoplanets to dying stars, distant galaxies and nebulae. Seen in this photograph, the Keck I and Keck II telescopes dazzle the skies with their adaptive optics lasers -- a system that helps cancel out the turbulence of the Earth's atmosphere, bringing science some of the clearest views attainable by a ground-based observatory.
To celebrate the last two decades of incredible science, Discovery News has assembled some of the most impressive imagery to come from Keck.
William Merline, SWRI / W.M. Keck Observatory
Starting very close to home, the Keck II captured this infrared image of asteroid 2005 YU55 as it flew past Earth on Nov. 8, 2011.
Larry Sromovsky (University of Wisconsin)
Deeper into the solar system, the Keck NIRC2 near-infrared camera captured this beautiful observation of the oddball Uranus on July 11-12, 2004. The planet's north pole is at 4 o'clock.
W.M Keck Observatory/NASA/JPL-G.Orton
This is a mosaic false-color image of thermal heat emission from Saturn and its rings on Feb. 4, 2004, captured by the Keck I telescope at 17.65 micron wavelengths.
Antonin Bouchez (W. M. Keck Observatory)
A nice image of Saturn with Keck I telescope with the near infrared camera (NIRC) on Nov. 6, 1998. This is a composite of images taken in Z and J bands (1.05 and 1.3 microns), with the color scaling adjusted so it looks like Saturn is supposed to look to the naked eye.
Antonin Bouchez, W.M. Keck Observatory
This is Saturn's giant moon Titan -- a composite of three infrared bands captured by the Near Infrared Camera-2 on the 10-meter Keck II telescope. It was taken by astronomer Antonin Bouchez on June 7, 2011.
W. M. Keck Observatory/SRI/New Mexico State University
Another multicolored look at Titan -- a near-infrared color composite image taken with the Keck II adaptive optics system. Titan's surface appears red, while haze layers at progressively higher altitudes in the atmosphere appear green and blue.
Mike Brown, Caltech / W.M. Keck Observatory
This image of Neptune and its largest Tritan was captured by Caltech astronomer Mike Brown in September 2011. It shows the wind-whipped clouds, thought to exceed 1,200 miles per hour along the equator.
A color composite image of Jupiter in the near infrared and its moon Io. The callout at right shows a closeup of the two red spots through a filter which looks deep in the cloud layer to see thermal radiation.
Christian Marois, NRC and Bruce Macintosh, LLNL/W. M. Keck Observatory
HR 8799: Three exoplanets orbiting a young star 140 light years away are captured using Keck Observatory's near-infrared adaptive optics. This was the first direct observation by a ground-based observatory of worlds orbiting another star (2008).
Bob Goodrich, Mike Bolte, and the ESI team
Now to the extremes -- an image of Stephan's Quintet, a small compact group of galaxies.
W.M. Keck Observatory
The Egg Nebula: This Protoplanetary nebula is reflecting light from a dying star that is shedding its outer layers in the final stages of its life.
W. M. Keck Observatory
This is WR 104, a dying star. Known as a Wolf Rayet star, this massive stellar object will end its life in the most dramatic way -- possibly as a gamma-ray burst. The spiral is caused by gases blasting from the star as it orbits with another massive star.
W. M. Keck Observatory/UCLA
Narrow-field image of the center of the Milky Way. The arrow marks the location of radio source Sge A*, a supermassive black hole at the center of our galaxy.
Dr. Mark Morris (UCLA) Keck II, Mirlen instrument
A high resolution mid-infrared picture taken of the center of our Milky Way reveals details about dust swirling into the black hole that dominates the region.
Mansi Kasliwal, Caltech and Iair Arcavi, Weizmann Institute of Science/W. M. Keck Observatory
A false-color image of a spiral galaxy in the constellation Camelopardalis.
A scintillating square-shaped nebula nestled in the vast sea of stars. Combining infrared data from the Hale Telescope at Palomar Observatory and the Keck II telescope, researchers characterized the remarkably symmetrical “Red Square” nebula.
ESA, NASA, J.-P. Kneib (Caltech/Observatoire Midi-Pyrenees) and R. Ellis (Caltech)/W. M. Keck Observatory
Galaxy cluster Abell 2218 is acting as a powerful lens, magnifying all galaxies lying behind the cluster's core. The lensed galaxies are all stretched along the shear direction, and some of them are multiply imaged.
UC Berkeley/NASA/W. M. Keck Observatory
The central starburst region of the dwarf galaxy IC 10. In this composite color image, near infrared images obtained with the Keck II telescope have been combined with visible-light images taken with NASA’s Hubble Space Telescope.
— The event begins Tuesday at about 3:09 p.m. PDT (6:09 p.m. EDT or 2209 GMT) and lasts nearly seven hours.
— Venus will cross the sun and observers on seven continents will be able to see it.
— The requirements for photographing the transit are the same as those for imaging sunspots or a partial solar eclipse.
Witnessed only seven times since the time of Galileo, Venus's solar crossing on Tuesday (June 5) is a rare and historic event that shouldn't be missed. Unless modern science discovers a way to delay or halt the aging process, this will be the last Venus transit we'll ever get to see in our lifetime — the next transit won't take place until 2117, or 105 years from now.
The transit of Venus in 2012 will begin at about 3:09 p.m. PDT (6:09 p.m. EDT or 2209 GMT) and last nearly seven hours as Venus crosses the face of the sun, according to NASA. Observers on seven continents, including part of Antarctica, will be able to see the Venus transit, though for some skywatchers the event will occur on Wednesday, June 6, due to the International Date Line.
But how can Venus transit photographers capture the rare celestial sight safely? The basic requirements for photographing the transit with a digital camera are very much the same as those for imaging sunspots or a partial solar eclipse.And as luck would have it, these same tips can help you snap photos of a partial lunar eclipse of Monday (June 4), too!
Here are things to keep in mind when shooting this much-anticipated celestial alignment for posterity:
1. Filter! Filter! Filter!Protect your eyes and equipment by using a proper, visually safe solar filter to cut down the sun's intense brightness and heat. Use a No. 14 welder's glass filter or purchase special solar filters — made of aluminized polyester or black polymer film or metal-coated glass or resin — from reputable dealers such as Thousand Oaks, Astro-Physics, Kendrick Astro Instruments, and Orion Telescopes & Binoculars. Make sure the filter is securely mounted on the front of your telephoto lens or telescope.
Color-negative or slide film, smoked glass, ordinary sunglasses, Mylar balloons, space blankets, black plastic trash bags, CDs, and polarizing or neutral-density (ND) filters used in regular photography are considered not safe for solar viewing, and therefore should not be used. [How to Safely Photograph the Venus Transit (Photo Guide)]
2.Use a telescope or telephoto lens: Decide what you want to record — the whole disk of the sun with the tiny pitch-black silhouette of Venus in it or close-ups of the ingress (entry) or egress (exit) of Venus' disk along the edge of the sun to try and record the so-called "black-drop" effect. In this elusive phenomenon, first reported by astronomers during the transit in 1761, as Venus's silhouette makes contact with the solar disk's edge, Venus's outline seems to get distorted into a teardrop shape.
To produce a reasonably large image of the sun with a digital camera, you'll need a telephoto lens or telescope with a focal length of 500 to 1,000 millimeters, or even longer. You'll also need a tripod or mounting that is beefy enough to carry the load.
You can boost the magnification of your telephoto lens using a 2x teleconverter. For the telescope, try magnifying the image with an eyepiece or Barlow lens.
3. Check your focus:Focusing is especially critical when you use a telescope or long telephoto lens that doesn't have a fixed "infinity" setting. Don't rely on the camera's auto-focus function; switch to manual (M) mode instead and use the edge of the sun or nearby sunspots for focusing. Once you achieve sharpest focus, tape down your lens's focus ring (or lock the telescope focuser) to prevent it from accidentally being moved during the transit. Be sure to recheck your focus as the transit progresses since daytime heating can cause the focus to shift slightly. If needed, wrap a space blanket around your gear to keep it cool.
4. Shoot at high resolution:A digital camera's image quality and resolution is determined by the number of pixels in its sensor (expressed in millions of pixels, or megapixels). The more pixels the camera has, the better the quality of the image will be. To take full advantage of the camera's capability, shoot images using high-resolution formats such as the highest-quality JPEG or uncompressed TIFF or RAW files. This will allow you to make 8 x 10, 11 x 14, or larger, prints while retaining the images' overall sharpness and smooth tones. [Venus Transit of 2004: 51 Amazing Photos]
5. "Bracket" your exposures:You can either use the camera's auto-exposure mode or manual (M) mode to determine your exposure settings. If you prefer to do it manually, try various combinations of shutter speed, f/stop, and ISO speed — a technique known as "bracketing" — and see which ones would come out best and use that as a guide. Don't be afraid to experiment.
To capture the moment of ingress and/or egress, switch your camera to continuous shooting or "burst" mode so it can take many shots in quick succession. Be sure to test your equipment and practice your procedure ahead of the transit. Try to do your testing around the same time of day the transit will occur to determine the best exposure to use.
6. Try to minimize vibrations: The slapping of the viewfinder mirror in DSLR cameras can cause blurry images, especially at slow shutter speeds. To reduce camera jitter, operate the shutter button with a long mechanical or electronic cable release, or use the camera's delay timer. If possible, lock the viewfinder mirror up before each exposure (consult your camera manual on how to do this). Use an ISO setting of 400 or 800 to keep your exposures short. [Amazing Video of the 2004 Venus Transit]
Choose an observing site that is far from vehicular or pedestrian traffic and is sheltered from the wind. A geared head or fluid head on a tripod can eliminate jerky movements and make it easier to manually follow the sun as it moves slowly across the sky. To improve the tripod's stability, hang your backpack, camera bag, water jug or other weights under its center post. You can also place rubberized footpads or mats under each tripod leg to absorb ground or wind vibrations.
7. Bring spare batteries and memory cards: On Venus transit day, be sure to use a fully charged battery. Keep a spare one as backup since the event can last for an hour or more, depending on your location. (In Hawaii and Alaska, the transit will last approximately 6 hours 40 minutes from start to finish.)
Digital cameras can be power hogs, especially if you use the LCD screen constantly. If your camera has an AC power adapter and there's a wall outlet nearby, use them so you don't have to worry about depleting your battery during the transit.
High-resolution images take up a lot of memory so use fast, large-capacity storage cards (4 to 8 gigabytes, or more) to avoid running out of memory at a critical time.
8. Shoot the transit in hydrogen-alpha:Specialized hydrogen-alpha telescopes, such as the Coronado PST and SolarMax II series from Meade Instruments, provide stunning details on the sun, which make for a dramatic backdrop to Venus' disk.
Unlike ordinary, unfiltered light from the sun, also known as "white light," H-alpha is the red light emitted by hydrogen atoms in the sun's atmosphere, called the chromosphere, at a wavelength of 656.3 nanometers. If there are large solar prominences along the edges of the sun, it might be possible to glimpse Venus against a prominence right before the planet's disk enters, and right after it leaves, the sun's disk.
9. Shoot with video: As with digital cameras, you'll need a proper solar filter over the camcorder's lens. Many camcorders have zoom lenses with up to 40x or more optical magnification. To videotape the transit, simply mount the solar-filtered camcorder on a tripod, aim it at the sun and zoom in to its highest power. Use the camcorder's manual settings, if available, to prevent the sun's image from getting overexposed. Take short clips every five minutes or so to create a short time-lapse movie of the Venus transit.
High-end DSLRs as well as smartphones are also capable to shooting still shots or HD videos of the transit through a solar-filtered telescope.
10. Check the latest weather forecast: Get the latest weather update from websites such as the National Weather Service, AccuWeather, The Weather Channel or Weather Underground. You can also view the latest weather images and animations from NOAA's GOES satellites to help you plan on where to go in case clouds or rain showers threaten your intended Venus transit observing site.
After the transit, be sure to backup all your still images and/or videos right away on DVDs, flash drives or your laptop's hard drive so you don't lose any of your precious mementos.
Partial lunar eclipse photography tips
As an added celestial treat to skywatchers, a partial eclipse of the moon will occur on Monday — the eve of the transit of Venus.
A partial lunar eclipse takes place when the full moon passes through the dark central part of Earth's shadow, called the umbra, and gets partly covered by the umbra.
Observers in eastern Australia and the Pacific will have a ringside view of the entire two-hour-long eclipse. They will see the moon immersed more than a third of the way (37 percent) into the umbra at maximum eclipse. [Lunar Eclipse of June 4: Observer's Guide (Images)]
Most of North and South America will see the moon set before the eclipse ends; eastern Asia will miss the start of the eclipse since it occurs before the moon rises.
In northeastern United States and eastern Canada, no part of the umbral eclipse will be visible since the event starts after the Moon had set. Western Canada and the U.S. West Coast offer the next-best views — the moon doesn't set there until after mid-eclipse.
You can use the same transit setup and technique to photograph the partial lunar eclipse, minus the solar filter, of course. You will not see anything if you leave the solar filter on! Be sure to put it back on before you shoot the transit the following day.
Good luck and clear skies!
Veteran astrophotographers and transitophiles Imelda Joson and Edwin Aguirre are planning to capture the transit from Southern California as the sun sets over the Pacific.
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