Friday, September 25, 2009

Combining the Vari-N-Duo with a bit of software magic opened up the shadows

During his most recent workshop in Great Smoky Mountain National Park, fine-art nature photographer (and former magician) Tony Sweet made this image by slowing his exposure down to 10 seconds. "By using my Singh-Ray Vari-N-Duo," says Tony, "I was able to convey the surging action of the mountain stream while I also controlled the specular highlights reflecting off the stones and moss to fully reveal their true colors. That's because the Vari-N-Duo filter combines the classic Vari-ND variable neutral density filter to slow my shutter speeds anywhere from about two to eight f-stops with the LB Warming Polarizer which lets me control the glare from the water and wet rocks.

"I could see that this scene presented an interesting opportunity to merge two different techniques -- one hardware and one software. In mountain streams, where there are large boulders, the undersides of the boulders are very dark. If the water is running well, it is very bright, even on overcast days. So, therein lies our conundrum. Expose correctly for the water and the rock undersides become black holes or expose to bring out some detail under the boulders and the water loses all detail in the white areas.

"This is when my HDR software comes in handy. But now, with the moving water, we have another problem: when the short exposures (-2ev) and long exposures (+2ev) are captured in an HDR series, the water can often look unreal, almost abstract, and even visually distracting (especially in this type of quiet stream scene). In order to get sufficiently long exposures on every image in my HDR series, the Vari-N-Duo was the obvious tool to be used. The polarizer also helped tone down the glare from the rocks.

"My base exposure in the 5-image HDR series was 1 second @f/22. That would give me a 1/4 second @ -2ev, which wasn’t slow enough to keep the water smooth on all 5 exposures. I figured out that if my base exposure could actually be 4 seconds, my longest exposure would be 15 seconds, no problem there, but more importantly my shortest exposure would be 1 second. Adding the Singh-Ray Vari-N-Duo slowed the exposure sequence so that my shortest exposure of one second easily blended with the other longer exposures to get the same smooth feel as in the natural image above. The blending of all five HDR images and some tone mapping in post-production resulted in this final 'super-real' HDR image, where the undersides of the boulders are well exposed and the water is practically identical. The scene was captured in the Tremont area in the Great Smoky Mountains with my Nikon D3X and 24-70mm f/2.8 lens.

"Contrary to some in this age of digital imaging who assume their computers erase the need for using filters in the field," says Tony, "I continue to rely on all my Singh-Ray filters to help achieve the images I see in my imagination." To explore the wide range of Tony's photographic pursuits, including his books, workshops and fine art images, you'll want to visit his website and blog.

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