John Austin Photography

Bokeh, the quality of these unfocused zones is something being misrepresented by some  photographers on the Wise and Wonderful Web at the moment, so a moment of clarification

Bokeh, more accurately Boke Aji, translates as "The Scent of Mist", meaning the quality of out of focus zones, rather than the simple observation that out of focus areas are not in focus, whch is what Depth of Field, DoF* is about.

Boke Aji is a function of spherical aberration, and the best descricription of it I can find is in Photographic Lenses, Beck and Andrews pub cira 1900. It clearly explains why some lenses have objectionable "soap bubble bokeh"

* Depth of Focus is not the same thing, Depth of Field is what happens in space, Depth of Focus is the depth of sharpness at the film plane. This is critical for wide angle lenses, less so for long ones