What is Sepia Tone?

Caleb Agnew, like many professional photographers of his era, worked exclusively in sepia tone, a technique which gained popularity with the rise of paper-based photo printing and gradually disappeared over the first decades of the 20th century. According to "Wikipedia" (the free Internet encyclopedia)....

Sepia tone is a type of monochrome photographic image in which the picture appears in shades of brown as opposed to greyscale as in a black-and-white image. It was originally produced by adding a pigment made from the Sepia cuttlefish to the positive print of a photograph taken with any number of negative processes. The chemical process involved converts any remaining metallic silver to a sulphide which is much more resistant to breakdown over time. This is why many "old time" photographs are sepia toned—those are the ones that have survived until today.

Presumably photographers stopped using sepia tone process as the process for "fixing" greyscale photographic emulsions improved. Use of sepia tone printing diminished quickly during the first decades of the 20th Century and had all but disappeared by the 1930s and the advent of Kodachrome (i.e. color) film and printing processes.

Today sepia tone has made somewhat of a comeback, though primarily as a digital process rather than a chemical one. Many modern photographers have found that adding a sepia tint gives their photographs more of an "old timey" or "artsy" look than plain greyscale (which is itself considered a more artistic treatment than color). Adobe Photoshop and similar image manipulation software programs offer various ways to add sepia tone to a print, but some purists maintain that the effect is not the same, and thus not as good as, an old-fashioned paper photograph chemically finished with a sepia tone process.

Below is a modern sepia tone digital photo made by Dutch photographer Inge Dobbe: