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Tuesday, March 26, 2013

High-Tech Landscapes

Improved Dynamic Range • Expanded ISO • Extended Depth Of Field • High-Resolution Panoramas Digital Ground Glass

Labels: How-ToColumnTech Tips
Extended Depth Of Field
I love it when new technology re-defines the rules of photography, and in my book, multiple-image stacking for an unlimited range of sharpness changes everything we thought we knew about depth of field. The limitations of depth of field (that is, the distance within an image between the nearest and farthest objects that appear acceptably sharp) are most apparent in macro photography because at higher magnifications the zone of sharpness is miniscule. But imagine that you could focus that zone of sharpness again and again, moving through the subject in slices, and then composite all those sharp images into one, completely in-focus photograph.

This process, called stacking, is a technique that can be applied with excellent results in landscape photography. The standard example, and a common landscape situation, is when you have an important foreground, such as wildflowers; your center of interest, such as a cactus, is in the mid-range; and the snowcapped mountain range in the background is important to the location. Yes, it's classic David Muench. He accomplished this beautifully with a large-format camera technique that controls the plane of focus. In the digital age, we can achieve a similar result with a DSLR coupled with an expensive tilt/shift lens, or we can take a series of captures focused at overlapping planes throughout the scene, from foreground to background. Composited in post-capture software that discards all out-of-focus elements and retains only sharp details, the result is an image of nearly unlimited depth of field and sharpness. No additional equipment is needed to do this, but compositing software is necessary. I've used Adobe Photoshop (www.photoshop.com), Helicon Focus (www.heliconsoft.com) and Zerene Stacker (www.zerenesystems.com) with excellent results.

George Lepp captured this GigaPan image of Mount McKinley in Denali National Park & Preserve, Alaska. The panorama is comprised of 105 captures from a Canon EOS 5D Mark II and an EF 100-400mm lens at 400mm, which rendered a 5.26 GB file. The final 8-bit image is about 1 GB in size and has been printed to 20 feet in length with excellent quality. The panorama's extremely high resolution is evident in the single-image capture of the south summit (inset), only one of the original 105 frames.
High-Resolution Panoramas
There's nothing new about the concept of panorama images; we experience one every time we scan the horizon. But we've come a long way from the time when a panorama was composed of several prints taped together, or when a swing-lens camera swept across the scene with its film moving in the opposite direction. If you're old enough, you'll remember all those class photos from elementary school.

Now there are lots of ways to capture multiple images and compile them into one high-resolution panorama. We still have to move the camera to capture the landscape, but mechanical advancements have given us some very precise tools with which to accomplish this. On the one hand, we can simply sweep some cameras, those with a built-in sweep panorama feature, across the scene and let the "camera" do the stitching on the fly. For the more technically inclined, Really Right Stuff (reallyrightstuff.com) offers a variety of specialty clamps, rails and heads to facilitate manual capture of panoramas in multiple rows and columns.

GigaPan Systems (www.gigapan.com), Kolor (www.kolor.com) and Clauss (www.dr-clauss.de/en/) manufacture automated systems that accommodate digital cameras from advanced compact cameras to professional DSLRs with big telephotos attached. The units can be programmed to self-calculate the number and distribution of images necessary to cover your subject, depending upon the focal length of your lens. You even can achieve high-resolution HDR panoramas by setting the system to capture several images at varying exposures in each position and then compositing each segment of the panorama before assembly.


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