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Tuesday, September 28, 2010

X Marks The Spot

New tools to guide you to the perfect place for the perfect photograph

Labels: How-ToGPS

This Article Features Photo Zoom

Monument Basin along the White Rim, Island in the Sky District, Canyonlands National Park, Utah.
Enter the first date that matched our search criteria, March 21, 2011. In Details view, drag the time-of-day marker along the timeline to the moment of sunrise. You also can click the forward and backward arrows below the timeline to jump from one celestial event (sunrise, moonset, etc.) to the next. Stop when the panel displays “sunrise.” A black line now extends from the Primary Marker—your position atop Twin Sisters—toward the moon at the moment of sunrise (not the position the moon will have when it sets 41 minutes later).

Bingo! At the moment of sunrise, the moon will be directly over the saddle between Longs Peak and nearby Mount Meeker—close enough to Longs that you can use a telephoto lens to magnify the moon, yet still have Longs and Meeker in the frame.

But wait—you have to check one more thing. Drop the Secondary Marker where the black line indicating moon direction crosses the saddle between Longs and Meeker. In the info panel, you can see that the altitude of that saddle, measured from the summit of Twin Sisters, is 4.3 degrees. Now look at the altitude of the moon at sunrise—6.7 degrees. Perfect! The moon will be 2.4 degrees above the saddle at the moment of sunrise. Since the moon subtends an angle of 0.5 degrees, that means it will be five moon diameters above the horizon at sunrise. If the sky is clear to the east at sunrise, you should be able to make a strong “triangular” composition with three main points of interest: the moon, the summit of Longs and the summit of Meeker. Add some warm sunrise light on the peaks, and you have a winner. Checking the other four dates provided by Heavenly-Opportunity shows March 21 to be the best day in 2011 for shooting moonset over Longs Peak.

The Photographer’s Ephemeris does have some limitations. The elevation information comes primarily from a grid with a data point every 90 meters horizontally. If the jagged summit you’re planning to shoot from falls in between data points, the program may give an inaccurate elevation. In extreme cases (Longs Peak, for example), the summit elevation may be off by 500 vertical feet. If your shot has very tight tolerances, use a USGS 7.5-minute quad and a little old-fashioned trigonometry to calculate the best day and time to make the trip. Another limitation: You need an Internet connection to make the program work. And you can’t print tables of sun and moon data. Heavenly-Opportunity can, however. I usually start my planning with The Photographer’s Ephemeris, then make Heavenly-Opportunity printouts for the dates of my trip. Using these two tools together makes it much easier to be in the right place at the right time.

To see more of Glenn Randall’s work, visit www.glennrandall.com.


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