Here's a new image, made last Tuesday evening near Olmsted Point in Yosemite. My friend Mike Osborne calls this the "Bowsprit" tree. What? I didn't get it either until he explained that a bowsprit is the bent figure with arms splayed back at the bow of old sailing ships. Okay, yeah, this does sort of resemble that.
Anyway, I "painted" this wonderful tree with a flashlight, and used the image-stacking technique to get noise-free star trails. With image stacking the idea is to take a series of short exposures and blend them together, rather than doing one long one. The total exposure time here is about 90 minutes, but one exposure that long would end up being quite noisy. Instead I took 24 four-minute exposures, with only a one-second interval between them. So each of those four-minute exposures has little noise.
I then stacked all 24 frames as separate layers in Photoshop, and changed the blending mode in all but the bottom layer to "Lighten." (There's also specialized software for doing the blending, but I've never tried it.) Rick Whitacre used this technique for his beautiful image of Upper Cathedral Lake that I critiqued last October, and you can find links to more information about image stacking in that critique.
Like a lot of night photographs, making this involved considerable work. But the great thing about night photography is that it allows your imagination to take flight. You have to visualize how your lighting and the sky's motion will come together, come up with an idea that might work—and, you hope, capture some of that nighttime mystery—and then execute that idea. When the result matches your visualization it's really satisfying.
Michael Frye is a professional photographer specializing in landscapes and nature. He is the author and photographer of The Photographer’s Guide to Yosemite, Yosemite Meditations, and Digital Landscape Photography: In the Footsteps of Ansel Adams and the Great Masters, plus the eBook Light & Land: Landscapes in the Digital Darkroom. He has written numerous magazine articles on the art and technique of photography, and his images have been published in over thirty countries around the world. Michael has lived either in or near Yosemite National Park since 1983, currently residing just outside the park in Mariposa, California.