William A. Bentley of Jericho, Vermont, dedicated his entire adult life to taking photographs of snowflakes. Bentley was born in 1865 on a New England farm, and photographed his first snow crystal at the age of 20. It was a passion that lasted over 40 years, during which time, using his camera through a microscope, Bentley built up a collection of 6,000 snowflake pictures.
The origins of modern photography go back to the ancient concept of the "camera obscura", a device originally comprising a darkroom into which light was allowed to pass through a small hole, allowing an image of the scene outside to be projected on the opposite wall. The idea was miniaturised by 16th century artists as an aid to fathoming the mysteries of perspective, and the invention of lenses not long afterwards allowed the image to be sharply focused.
It was not until the 19th century, however, that techniques were perfected of preserving the images thus conjured up. In the late 1830s, the Frenchman Louis Daguerre, with his daguerreotypes, developed a way of fixing the image onto metal, and during the following decade photography as we know it today became reality.
The key to a good photograph was summed up by Robert James Waller through the words of Robert Kincaid in The Bridges of Madison County: "He began to see that light was what he photographed - not objects: the objects were merely vehicles for reflecting the light from which his photographs were ultimately made."
As the sun travels across the sky between dawn and dusk, the quality of its reflected light changes by the hour. There is a period before dawn, often called pre-dawn, which is a kind of twilight, when the diffuse light from the eastern sky delivers very weak shadows. Scenes often have a bluish tinge, resulting from the early-morning mists.
As the first rays of sunlight break across the horizon, long thin shadows rake across the ground, revealing form and texture in the landscape. But as the sun climbs higher in the sky and shadows shrink, the colours lose their vivid individuality. A pervasive harshness is in evidence, and human subjects have a pale and pasty look; hidden by hard shadows, their eyes often appear in midday photographs as black and lifeless voids.
By mid-afternoon, however, the descending sun and lengthening shadows once again impart a three-dimensional feel to any landscape. And when the sun has disappeared below the western horizon, photographers often seek out lakeland scenery and seascapes, to capture the blue and pink and purple shades of twilight reflected in the water.