In the Field

Down the Hatch! Findlay Creek, BC, Canada. April 1, 2007.

I've included this image to describe the lens characteristic known as "bokeh". Everyone has an intuitive idea of what we mean of by "image sharpness". In some respects, "bokeh" (which is derived from the Japanese term "boke") is the opposite - it refers to the quality of the out-of-focus zones. Images that have smooth out-of-focus zones without jagged lines or sharp edges are said to have "good bokeh." In a lens with good bokeh the edges of any background objects should be blurred and undefined. Background point sources of light should also smoothly blend into the background.

The image above was taken with one of Nikon's top lenses bokeh-wise: the AFS-Nikkor 200 mm f/2 G ED-IF VR lens. The image exhibits what is meant by "good bokeh". Notice how the background objects are completely indistinct and blur into one another almost seamlessly. The olive-green zone beneath the squirrel's tail is actually a Douglas Fir tree about 20 metres behind the squirrel. The cream-coloured zone to the right of the squirrel's head are rolling hills covered in brown grass. And, the blue zone along the top-right part of the image is NOT the sky - it's distant mountains. Notice also the consistent, gradual transition from tack sharp detail on the squirrel's head to the out-of-focus zones on the squirrel's tail and background. This is GREAT bokeh!

What produces bokeh? The explanation is quite technical, but it TENDS to be correlated with high quality lenses, and often most closely associated with fast telephoto lenses. It is also related to the shape of a lense's opening (or "aperture") - bokeh is most likely to be smooth and edgeless if the aperture is circular. Having a circular aperture is, in turn, correlated with the number of aperture blades and the curvature of the blades (with more blades and appropriately curved blades more likely to produce round apertures). But it also involves a lense's "circle of confusion" AND spherical aberration. Confused yet? If not, just check out a more detailed explanation of the causation of bokeh in any or all of the following sources: What is Bokeh? on Ken Rockwell's website, or "bokeh" on Answers.com, or for the most confusion, "Understanding Boke" by Harold M. Merklinger!

Behind the Camera

Down the Hatch! Findlay Creek, BC, Canada. April 1, 2007.

Digital Capture; Uncompressed RAW (NEF) format; ISO 100.

Nikon D2Xs with Nikon 200mm f/2G ED-IF AF-S VR lens lens (300 mm equivalent with digital conversion factor) supported on Gitzo 1348 carbon fibre tripod with Wimberley head. SB-800 main flash (master) equipped with Better Beamer extender mounted on Really Right Stuff flash bracket. VR turned to "On" and in "Normal" mode.

1/160s @ f4.5; No compensation from matrix-metered exposure setting; balanced i-TTL flash exposure with -0.67 stop compensation on SB-800.

At the Computer

Down the Hatch! Findlay Creek, BC, Canada. April 1, 2007.

RAW Conversion to 16-bit TIFF, including saturation enhancement, tone curve adjustment, and first-pass sharpening, using Phase One's C1 Pro.

Further digital correction on 16-bit TIFF file using Adobe's Photoshop CS3, including selective saturation enhancement, additional tone curve adjustment, and selective sharpening for web output.

Conservation

Down the Hatch! Findlay Creek, BC, Canada. April 1, 2007.

Ten percent of the revenue generated by this image will be donated to Wildsight.

Species Status in Canada*: This species is not designated as at risk.

The North American Red Squirrel (Tamiasciurus hudsonicus) is a small, rusty coloured squirrel distributed throughout most of Canada and in both the western mountains and Appalachian mountains of the United States. While the Red Squirrel is not considered under any threat as a species, some local populations are declining as the larger and more ecologically aggressive Grey Squirrel expands its range. In Calgary, Alberta, for example, the Grey Squirrel has replaced the Red Squirrel throughout most of the city over the past 30 years or so.

This Red Squirrel was photographed in the Columbia Valley of the East Kootenays. While this species is not currently not considered at risk in the Kootenays, it is vulnerable to habitat loss due to logging activities. Many ecosystems within the Columbia Valley face development pressure, including pressure from logging operations. Wildsight is an effective conservation organization that protects biodiversity and promotes sustainable communities in Canada's Columbia and Rocky Mountains. Support for Wildsight, through donation or becoming a member, will help ensure that they remain effective in their efforts to conserve threatened or endangered species and ecosystems.

*as determined by COSEWIC: The Committee on the Status of Endangered Wildlife in Canada.