Details in harsh light

I recently took the opportunity to visit Palo Duro canyon in the Texas panhandle, a place I’d heard a lot about while living in the state but didn’t go see.  It is the second largest canyon in the United States (that other one in Arizona is bigger), the million year efforts of one branch of the Red River to cut through many layers of the Plains.  Wandering around the park I was struck by the similarities of the layers with the ones I saw in Badlands National Park, another erosion areas of the Plains.  Bands of grey, yellow, orange and red frame the slopes and walls of both, revealing the common heritage at the bottom of a primeval ocean.

Of course I wanted some images from this unique landscape but the lighting was very harsh, not uncommon in the country’s center.  While the sun was high enough to light the valley floor it was hard on the walls.  When the light was low enough to bring out the colors the angle cast strong shadows on the lower levels.  Too wide a dynamic range for a single exposure so obviously a HDR technique would be needed.

A single wide-angle image would not convey the level of detail I wanted so I knew the final image would be a panoramic.  There was little movement in the scene I wanted so I decided to try a technique I learned from George Lepp at a NANPA meeting in 2010.  He was showing off a huge image made by creating multiple HDR images that are stitched together as a panoramic.

This image is a stitched panoramic using 6 HDR images.  For each HDR image I made 5 images of differing exposures (correct exposure, +0.7, +1.4, -0.7, -1.4) so a total of 30 images.  I held the aperture at f/10 to get my desired depth of field and changed the shutter speed to adjust exposures.  My camera (as most DSLR’s) has a setting where I can automatically make some number of exposures over and under the correct exposure.  I set it for the 5 images and range indicated and then simply set it on rapid shooting (motor drive for you film fans) and held the shutter down for 5 shots.  I used my 14-54mm lens at 41mm (82mm at a 35mm equivalent).  My camera was horizontal on a tripod and I used a remote shutter release to minimize vibration.  For my panoramics I try to overlap the sequential images by about 30% to give the software plenty of data to blend.

George’s workflow is to create the HDR image of each section of the panoramic first, and then stitch the resulting HDR images together.  I used the NIK HDR Efex Pro plug-in for Photoshop CS5 to create the HDR images with 0% tone compression and about 40% Natural image processing.  I then selected the 6 HDR images and dropped them into Photoshop’s panoramic tool to stitch them together.  The resulting file is around 178Mb in size and 11158×2785 pixels in dimension, giving me a final print at 300dpi of around 37×9.25″.

As you can see I was able to capture much of the colored bands on the canyon walls while retaining detail in the shadows.  Overall the image portrays the dimensionality of the canyon from this perspective.  Since it is cut into the flat plains the canyon rim is the highest point around – a little higher vantage point would allow a more 3D look to the image but I doubt they want an intruding tower in the park.  The image looks like I cut some of the top off but that’s how flat the land is around the canyon and with nothing interesting in the sky I just cropped it all out.  Now I see it was perhaps a little too much cropping off the top – need to leave more sky to show a definite end to the landscape.

I’m pleased with how this technique worked out and will certainly use it again when the circumstances allow.


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