Capturing the Elusive Green Flash

Steve Cullen

After trying to capture the elusive "green flash" for many years, I was finally successful on a trip to Hawaii in mid-October 2005. In fact, I was able to capture not just a single image (Fig. 1) but a 10-frame sequence (Fig. 2) showing the flash from beginning to end over a 5-second period.

To get this shot, I used a Nikon D2X with an 80-400 mm VR lens (@ 400mm, f/5.6, 1/640 second exposure, ISO 640) and a 2x tele-converter. I processed the images in Adobe Photoshop CS2 and created an animated GIF (Fig. 2) to better show the sequence.

For those not familiar with the green flash, there are many places on the web that describe it in great detail. In short, the green flash is an optical phenomenon caused by the refraction of the Sun's light by the atmosphere. The Earth's atmosphere bends each wavelength of light by different amounts. Red is bent the least while green is refracted more. Sometimes a "blue flash” can be seen, since blue is refracted even more than green. The flash occurs either just before sunrise or just after sunset on days where there is a clear view to the horizon. That's why the flash is so often seen over the ocean. However, the refraction of each wavelength of light is not enough to produce the observed effect. There also needs to be a warm layer of air just above the ground as in a mirage.

I am still very much an amateur photographer and have been taking as many pictures as I possibly can to sharpen my skills. I enjoy nature and sports photography and am working on astrophotography as well. I am drawn to photography because it allows me to combine my passions for nature, sports, science, technology, and creativity like no other hobby. It is an ongoing and limitless learning experience that I am sure will keep me challenged for the rest of my life.

For nature and sports images, I use a Nikon D2X with a variety of lenses, ranging from a 10.5 mm fisheye for wide-angle views to Nikon’s 200 mm f/2.0 “beast” lens for capturing fast action up close. For astrophotography I use a variety of telescopes, depending on what I am trying to image. When capturing the Sun and its prominences, I use a Takahashi TOA-130 refractor with a double-stacked Coronado Instruments SolarMax 90 hydrogen-alpha filter and a Santa Barbara Instruments STL-11000XM CCD camera. This all sits on top of a Takahashi NJP mount for accurate pointing and tracking.

When imaging stars, galaxies, and nebulae, I use either a Takahashi BRC-250 or an RC Optical Systems 16” Carbon-Truss Ritchey-Chretien telescope. These telescopes provide wide fields of view and top-quality optics. Imaging celestial objects is demanding and requires precision pointing and tracking, which Software Bisque’s Paramount ME mount gives me every time out. I also use a Santa Barbara Instruments STL-11000XM CCD with these scopes, employing red, green, blue, luminance, and nebula filters to capture color images.

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